MILTON AND GALILEO
After the death of his mother, which occurred in 1637, Milton expressed
a desire to visit the Continent, where there were many places of
interest which he often longed to see. Having obtained the consent of
his kind and indulgent father, he set out on his travels in April 1638,
accompanied by a single man-servant, and arrived in Paris, where he only
stayed a few days. During his residence in the French capital he was
introduced by Lord Scudamore, the English Ambassador at the Court of
Versailles, to Hugo Grotius, one of the most distinguished scholars and
philosophic thinkers of his age. From Paris Milton journeyed to Nice,
where he first beheld the beauty of Italian scenery and the classic
shores of the Mediterranean Sea. From Nice he sailed to Genoa and
Leghorn, and after a short stay at those places continued his journey to
Florence, one of the most interesting and picturesque of Italian cities.
Situated in the Valley of the Arno, and encircled by sloping hills
covered with luxuriant vegetation, the sides of which were studded with
residences half-hidden among the foliage of gardens and vineyards,
Florence, besides being famed for its natural beauty, was at that time
the centre of Italian culture and learning, and the abode of men eminent
in literature and science. Here Milton remained for a period of two
months, and enjoyed the friendship and hospitality of its most noted
citizens, many of whom delighted to honour their English visitor. He was
warmly welcomed by the members of the various literary academies, who
admired his compositions and conversation; the flattering encomiums
bestowed upon him by those learned societies having been amply repaid by
Milton in choice and elegant Latin verse.
Among those who resided in the vicinity of Florence was the illustrious
Galileo, who in his sorrow-stricken old age was held a prisoner of the
Inquisition for having upheld and taught scientific doctrines which were
declared to be heretical. After his abjuration he was committed to
prison, but on the intervention of influential friends was released
after a few days' incarceration, and permitted to return to his home at
Arcetri. He was, however, kept under strict surveillance, and forbidden
to leave his house or receive any of his intimate friends without having
first obtained the sanction of the ecclesiastical authorities. After
several years of close confinement at Arcetri, during which time he
suffered much from rheumatism and continued ill-health, aggravated by
grief and mental depression consequent upon the death of his favourite
daughter, Galileo applied for permission to go to Florence in order to
place himself under medical treatment. This request was granted by the
Pope subject to certain conditions, which would be communicated to him
when he presented himself at the office of the Inquisition at Florence.
These were more severe than he anticipated. He was forbidden to leave
his house or receive any of his friends there, and those injunctions
were so strictly adhered to that during Passion Week he had to obtain a
special order so that he might be able to attend mass. At the expiration
of a few months Galileo was ordered to return to Arcetri, which he never
left again.
An affliction, perhaps the most deplorable that can happen to any human
being, was added to the burden of Galileo's misfortunes and woes. A
disorder which had some years previously injured the sight of his right
eye returned in 1636. In the following year the left eye became
similarly affected, with the result that in a few months Galileo became
totally blind. His friends at first hoped that the disease was cataract,
and that some relief might be afforded by means of an operation; but it
was discovered to be an opacity of the cornea, which at his age was
considered unamenable to treatment. This sudden and unexpected calamity
was to Galileo a most deplorable occurrence, for it necessitated the
relinquishment of his favourite pursuit, which he followed with such
intense interest and delight. His friend Castelli writes: 'The noblest
eye is darkened which Nature ever made; an eye so privileged, and gifted
with such rare qualities that it may with truth be said to have seen
more than all of those eyes who are gone, and to have opened the eyes of
all who are to come.' Galileo endured his affliction with patient
resignation and fortitude, and in the following extract from a letter by
him he acknowledges the chastening hand of a Divine Providence: 'Alas!
your dear friend and servant Galileo has become totally blind, so that
this heaven, this earth, this universe, which with wonderful
observations I had enlarged a hundred and a thousand times beyond the
belief of bygone ages, henceforward for me is shrunk into the narrow
space which I myself fill in it. So it pleases God; it shall then please
me also.' The rigorous curtailment of his liberty which prompted Galileo
to head his letters, 'From my prison at Arcetri,' was relaxed when total
blindness had supervened upon the infirmities of age. Permission was
given him to receive his friends, and he was allowed to have free
intercourse with his neighbours.
Milton, during his stay at Florence, visited Galileo at Arcetri. We are
ignorant of the details of this eventful and interesting interview
between the aged and blind astronomer and the young English poet, who
afterwards immortalised his name in heroic verse, and who in his
declining years suffered from an affliction similar to that which befel
Galileo, and to which he alludes so pathetically in the following
lines:--
Thee I revisit safe,
And feel thy sovran vital lamp; but thou
Revisitest not these eyes, that roll in vain
To find thy piercing ray, and find no dawn;
So thick a drop serene hath quenched their orbs,
Or dim suffusion veiled.--iii. 21-26.
We can imagine that Galileo's astronomical views, which at that time
were the subject of much discussion among scientific men and professors
of religion, and on account of which he suffered persecution, were
eagerly discussed. It is also probable that the information communicated
by Galileo, or by some of his followers, may have persuaded Milton to
entertain a more favourable opinion of the Copernican theory. The
interesting discoveries made by Galileo with his telescope without doubt
formed a pleasant subject of conversation, and Milton enjoyed the
privilege of listening to a detailed description of these from the lips
of the aged astronomer. The telescope, its principle, its mechanism, and
the method of observing, were most probably explained to him; and we can
believe that an opportunity was afforded him of examining those in
Galileo's observatory, and of perhaps testing their magnifying power
upon some celestial object favourably situated for observation. Though
Milton has not favoured us with any details of his visit to Galileo, yet
it was one which made a lasting impression upon his mind, and was never
afterwards forgotten by him. 'There it was,' he writes, 'I found and
visited the famous Galileo, grown old, a prisoner of the Inquisition for
thinking in astronomy otherwise than the Franciscan and Dominican
licensers thought.' In years long after, when Milton, himself feeble
and blind, sat down to compose his 'Paradise Lost,' the remembrance of
the Tuscan artist and his telescope was still fresh in his memory.
By the invention of the telescope and its application to astronomical
research, a vast amount of information and additional detail have been
learned regarding the bodies which enter into the formation of the solar
system; and by its aid many new ones were also discovered. On sweeping
the heavens with the instrument, the illimitable extent of the sidereal
universe became apparent, and numberless objects of interest were
brought within the range of vision the existence of which had not been
previously imagined.
The Galilean telescope was invented in 1609. But the magnifying power of
certain lenses, and their combination in producing singular visual
effects, are alluded to in the writings of several early authors. The
value of single lenses as an aid to sight had been long known, and
spectacles were in common use in the fourteenth century. Several
mathematicians have described the wonderful optical results obtained
from glasses concave and convex, of parabolic and circular forms, and
from 'perspective glasses,' in which were embodied the principle of the
telescope. It is asserted that our countryman, Roger Bacon (1214), had
some notion of the properties of the telescope; but among those familiar
with the combination of lenses the two men who made the nearest approach
to the invention of the instrument were Baptista Porta and Gerolamo
Fracastro. The latter, who died in 1553, writes as follows: 'For which
reason those things which are seen at the bottom of water appear greater
than those which are at the top; and if anyone look through two
eye-glasses, one placed upon the other, he will see everything much
larger and nearer.' It is doubtful if Fracastro had any notion of
constructing a mechanism which might answer the purpose of a telescopic
tube. Baptista Porta (1611) is more explicit in what he describes. He
writes: 'Concave lenses show distant objects most clearly, convex those
which are nearer; whence they may be used to assist the sight. With a
concave glass distant objects will be seen, small, but distinct; with a
convex one, those near at hand, larger, but confused; if you know
_rightly_ how to combine one of each sort, you will see both far and
near objects larger and clearer.' He then goes on to say: 'I shall now
endeavour to show in what manner we may continue to recognise our
friends at the distance of several miles, and how those of weak sight
may read the most minute letters from a distance. It is an invention of
great utility, and grounded on optical principles; nor is at all
difficult of execution; but it must be so divulged as not to be
understood by the vulgar, and yet be clear to the sharp-sighted.' After
this, he proceeds to describe a mechanism the details of which are
confusing and unintelligible, nor did it appear to bear any resemblance
to a telescopic tube.
In a work published by Thomas Digges in 1591, he makes the following
allusion to his father's experiments with the lenses: 'My father, by his
continuall painfull practices, assisted with demonstrations
mathematicall, was able, and sundry times hath by proportionall glasses,
duely situate in convenient angles, not only discouered things farre
off, read letters, numbered peeces of money with the verye coyne and
superscription thereof cast by some of his freends of purpose, upon
downes in open fields; but also seuen miles off, declared what hath beene
doone at that instant in priuate places.' It must be admitted that if
Leonard Digges had not constructed a telescope, he knew how to combine
lenses by the aid of which a visual effect was created similar to that
produced by the use of the instrument.
The inventor of the telescope was a Dutchman named Hans Lippershey, who
carried on the business of a spectacle-maker in the town of Middelburg.
His discovery was purely accidental. It is said that the
instrument--which was directed towards a weather-cock on a church spire,
of which it gave a large and inverted image--was for some time exhibited
in his shop as a curiosity before its importance was recognised. The
Marquis Spinola, happening to see this philosophical toy, purchased it,
and presented it to Prince Maurice of Nassau, who imagined it might be
of service for the purpose of military reconnoitring. The value of the
invention was, however, soon realised, and in the following year
telescopes were sold in Paris. In 1609, Galileo, when on a visit to a
friend at Venice, received intelligence of the invention of an
instrument by a Dutch optician which possessed the power of causing
distant objects to appear much nearer than when observed by ordinary
vision. The accuracy of this information was confirmed by letters which
he received from Paris; and this general report, Galileo asserted, was
all he knew of the subject. Fuccarius, in a disparaging letter, says
that one of the Dutch telescopes had been brought to Venice, and that he
himself had seen it. This statement is not incompatible with Galileo's
affirmation that he had not seen the original instrument, and knew no
more about it than what had been communicated to him in the letters from
the French capital. It was insinuated by Fuccarius that Galileo had seen
the telescope at Venice, but, as he denied this, we should not hesitate
to believe in his veracity.
Immediately after his return to Padua, Galileo began to think how he
might be able to contrive an instrument with properties similar to the
one of which he had been informed; and in the following words describes
the process of reasoning by which he arrived at a successful result: 'I
argued in the following manner. The contrivance consists either of one
glass or of more--one is not sufficient, since it must be either convex,
concave, or plane. The last does not produce any sensible alteration in
objects; the concave diminishes them. It is true that the convex
magnifies, but it renders them confused and indistinct; consequently,
one glass is insufficient to produce the desired effect. Proceeding to
consider two glasses, and bearing in mind that the plane causes no
change, I determined that the instrument could not consist of the
combination of a plane glass with either of the other two. I therefore
applied myself to make experiments on combinations of the two other
kinds, and thus obtained that of which I was in search.' Galileo's
telescope consisted of two lenses--one plano-convex, the other
plano-concave, the latter being held next the eye. These he fixed in a
piece of organ pipe, which served the purpose of a tube, the glasses
being distant from each other by the difference of their focal lengths.
An exactly similar principle is adopted in the construction of an
opera-glass, which can be accurately described as a double Galilean
telescope. Galileo must be regarded as the inventor of this kind of
telescope, which in one respect differed very materially from the one
constructed by the Dutch optician. If what has been said with regard to
the _inverted_ weather-cock be true, then Lippershey's telescope was
made with two convex lenses, distant from each other by the sum of their
focal lengths, and all objects observed with it were seen inverted.
Refracting astronomical telescopes are now constructed on this
principle, it having been discovered that for observational purposes
they possess several advantages over the Galilean instrument. When
Galileo had completed his first telescope he returned with it to
Venice, where he exhibited it to his friends. The sensation created by
this small instrument, which magnified only three times, was most
extraordinary, and almost amounted to a frenzy. Crowds of the principal
citizens of Venice flocked to Galileo's house in order that they might
see the magical tube about which such wonderful reports were circulated;
and for upwards of a month he was daily occupied in describing his
invention to attentive audiences. At the expiration of this time the
Doge of Venice, Leonardo Deodati, hinted that the Senate would not be
averse to receive the telescope as a gift. Galileo readily acquiesced
with this desire, and, as an acknowledgment of his merits, a decree was
issued confirming his appointment as professor at Padua for life, and
increasing his salary from 500 to 1,000 florins. The public excitement
created by the telescope showed no signs of abatement. Sirturi mentions
that, having succeeded in constructing an instrument, he ascended the
tower of St. Mark's at Venice, hoping to be able to use it there without
interruption. He was, however, detected by a few individuals, and soon
surrounded by a crowd, which took possession of his telescope, and
detained him for several hours until their curiosity was satisfied.
Eager inquiries having been made as to where he lodged, Sirturi, fearing
a repetition of his experience in the church tower, decided to quit
Venice early next morning, and betake himself to a quieter and less
frequented neighbourhood.
The instrument was at first called Galileo's tube; the double eye-glass;
the perspective; the trunk; the cylinder. The appellation _telescope_
was given it by Demisiano.
Galileo next directed his attention to the construction of telescopes,
and applied his mechanical skill in making instruments of a larger size,
one of which magnified _eight_ times. 'And at length,' he writes,
'sparing neither labour nor expense, he completed an instrument that was
capable of magnifying more than _thirty_ times.'
Galileo now commenced an exploration of the celestial regions with his
telescope, and on carefully examining some of the heavenly bodies, made
many wonderful discoveries which added greatly to the fame and lustre of
his name.
The first celestial object to which Galileo directed his telescope was
the Moon. He was deeply interested to find how much her surface
resembled that of the Earth, and was able to perceive lofty mountain
ranges, the illumined peaks of which reflected the sunlight, whilst
their bases and sides were still enveloped in dark shadow; great plains
which he imagined were seas, valleys, elevated ridges, depressions, and
inequalities similar to what are found on our globe. Galileo believed
the Moon to be a habitable world, and concluded that the dark and
luminous portions of her surface were land and water, which reflected
with unequal intensity the light of the Sun. The followers of Aristotle
received the announcement of these discoveries with much displeasure.
They maintained that the Moon was perfectly spherical and smooth--a vast
mirror, the dark portions of which were the reflection of our
terrestrial mountains and forests--and accused Galileo 'of taking a
delight in distorting and ruining the fairest works of Nature.' He
appealed to the unequal condition of the surface of our globe, but this
was of no avail in altering their preconceived notions of the lunar
surface.
Perhaps the most important discovery made by Galileo with the telescope
was that of the four moons of Jupiter. On the night of January 7, 1610,
when engaged in observing the planet, his attention was attracted by
three small stars which appeared brighter than those in their immediate
neighbourhood. They were all in a straight line and parallel with the
ecliptic; two of them were situated to the east, and one to the west of
Jupiter. On the following night he was surprised to find all three to
the west of the planet, and nearer to each other. This caused him
considerable perplexity, and he was at a loss to understand how Jupiter
could be east of the three stars, when on the preceding night he was
observed to the west of two of them. Galileo was unable to reconcile the
altered positions of those bodies with the apparent motion of Jupiter
among the fixed stars as indicated by the astronomical tables. The next
opportunity he had of observing them was on the 10th, when two stars
only were visible, and they were to the east of the planet. As it was
impossible for Jupiter to move from west to east on January 8 and from
east to west on the 10th, he concluded that it was the motion of the
stars and not that of Jupiter which accounted for the observed
phenomena. Galileo watched the stars attentively on successive evenings
and discovered a fourth, and on observing how they changed their
positions relatively to each other he soon arrived at the conclusion
that the stars were four moons which revolved round Jupiter after the
manner in which the Moon revolves round the Earth. Having assured
himself that the four new stars were four moons that with periodical
regularity circled round the great planet, Galileo named them the
Medicean Stars in honour of his patron, Cosmo de' Medici, Grand Duke of
Tuscany. He also published an essay entitled 'Nuncius Sidereus,' or the
'Sidereal Messenger,' which contained an account of this important
discovery.
The announcement of Galileo's discovery of the four satellites of
Jupiter created a profound sensation, and its significance became at
once apparent. Aristotelians and Ptolemaists received the information
with much disfavour and incredulity, and many persons positively refused
to believe Galileo, whom they accused of inventing fables. On the other
hand, the upholders of the Copernican theory hailed it with
satisfaction, as it declared that Jupiter with his four moons
constituted a system of greater magnitude and importance than that of
our globe with her single satellite, and that consequently the Earth
could not be regarded as the centre of the universe.
When Kepler heard of this remarkable discovery, he wrote to Galileo and
expressed himself in the following characteristic manner: 'I was sitting
idle at home thinking of you, most excellent Galileo, and your letters,
when the news was brought me of the discovery of four planets by the
help of the double eye-glass. Wachenfels stopped his carriage at my door
to tell me, when such a fit of wonder seized me at a report which seemed
so very absurd, and I was thrown into such agitation at seeing an old
dispute between us decided in this way, that between his joy, my
colouring, and the laughter of both, confounded as we were by such a
novelty, we were hardly capable, he of speaking, or I of listening.... I
am so far from disbelieving in the existence of the four circumjovial
planets, that I long for a telescope to anticipate you, if possible, in
discovering two round Mars (as the proportion seems to me to require),
six or eight round Saturn, and perhaps one each round Mercury and
Venus.' The intelligence of Galileo's discoveries was received by his
opponents in a spirit entirely different from that manifested by Kepler.
The principal professor of philosophy at Padua, when requested to look
at the Moon and planets through Galileo's glass, persistently declined,
and did his utmost to persuade the Grand Duke that the four satellites
of Jupiter could not possibly exist. Francesco Sizzi, a Florentine
astronomer, argued that, as there are seven apertures in the head,
seven known metals, and seven days in the week, so there could only be
seven planets. To these absurd remarks Galileo replied by saying that,
'whatever their force might be as a reason for believing beforehand that
no more than seven planets would be discovered, they hardly seemed of
sufficient weight to destroy the new ones when actually seen.' Another
individual, named Christmann, writes: 'We are not to think that Jupiter
has four satellites given him by Nature in order, by revolving round
him, to immortalize the name of the Medici, who first had notice of the
observation. These are the dreams of idle men, who love ludicrous ideas
better than our laborious and industrious correction of the heavens.
Nature abhors so horrible a chaos, and to the truly wise such vanity is
detestable.' Martin Horky, a _protege_ of Kepler's, issued a pamphlet in
which he made a violent attack on Galileo. He says: 'I will never
concede his four new planets to that Italian from Padua though I die for
it.' He then asks the following questions, and replies to them himself:
(1) Whether they exist? (2) What they are? (3) What they are like? (4)
Why they are? 'The first question is soon disposed of by Horky's
declaring positively that he has examined the heavens with Galileo's own
glass, and that no such thing as a satellite about Jupiter exists. To
the second, he declared solemnly that he does not more surely know that
he has a soul in his body than that reflected rays are the sole cause of
Galileo's erroneous observations. In regard to the third question, he
says that these planets are like the smallest fly compared to an
elephant; and, finally, concludes on the fourth, that the only use of
them is to gratify Galileo's "thirst of gold," and to afford himself a
subject of discussion.'[7] Galileo did not condescend to take any notice
of this scurrilous production; but Horky, who imagined that he had done
something clever, sent a copy of his pamphlet to Kepler. In a few days
after he called to see him, and was received with such a storm of
indignation that he begged for mercy and implored his forgiveness.
Kepler forgave him, but insisted on his making amends. He writes: 'I
have taken him again into favour upon this preliminary condition, to
which he has agreed--that I am to show him Jupiter's satellites, _and he
is to see them_, and own that they are there.'
The evidence in support of the existence of Jupiter's satellites became
so conclusive that the opponents of Galileo were compelled to renounce
their disbelief in those bodies, whether real or pretended. The Grand
Duke, preferring to trust to his eyes rather than believe in the
arguments of the professor at Padua, observed the satellites on several
occasions, along with Galileo, at Pisa, and on his departure bestowed
upon him a gift of one thousand florins. Several of Galileo's enemies,
as a result of their observations, now arrived at the conclusion that
his discovery was incomplete, and that Jupiter had more than four
satellites in attendance upon him. Scheiner counted five, Rheita nine,
and other observers increased the number to twelve. But it was found to
be quite as hazardous to exceed the number stated by Galileo as it was
to deny the existence of any; for, when Jupiter had traversed a short
distance of his path among the fixed stars, the only bodies that
accompanied him were his four original attendants, which continued to
revolve round him with unerring regularity in every part of his orbit.
Galileo did not afford his opponents much time to oppose or controvert
with argument the discoveries made by him with the telescope before his
announcement of a new one attracted public attention from those already
known. He, however, exercised greater caution in disclosing the results
of his observations, as other persons laid claim to having made similar
discoveries prior to the time at which his were announced. He therefore
adopted a method in common use among astronomers in those days, by which
the letters in a sentence announcing a discovery were transposed so as
to form an anagram.
Galileo announced his next discovery in this manner, and which read as
follows:--
Smaismrmilme poeta leumi bvne nugttaviras.
This, when deciphered, formed the sentence:--
Altissimum planetam tergeminum observavi.
I have observed that the remotest planet is triple.
Galileo perceived that Saturn presented a triform appearance, and that,
instead of one body, there were three, all in a straight line, and
apparently in contact with each other, the middle one being larger than
the two lateral ones. In a letter to Kepler he remarked: 'Now I have
discovered a Court for Jupiter, and two servants for this old man, who
aid his steps and never quit his side.' Kepler, who excelled as an
imaginative writer, replied: 'I will not make an old man of Saturn, nor
slaves of his attendant globes; but rather let this tricorporate form be
Geryon--so shall Galileo be Hercules, and the telescope his club, armed
with which he has conquered that distant planet, and dragged him from
the remotest depths of Nature, and exposed him to the view of all.'
Continuing his observations, Galileo perceived that the two lateral
objects gradually decreased in size, and at the expiration of two years
entirely disappeared, leaving the central globe visible only. He was
unable to assign any reason for this peculiar occurrence, which caused
him much perplexity, and he expresses himself thus: 'What is to be said
concerning so strange a metamorphosis? Are the two lesser stars consumed
after the manner of the solar spots? Have they vanished and suddenly
fled? Has Saturn, perhaps, devoured his own children? Or were the
appearances, indeed, illusion or fraud, with which the glasses have so
long deceived me, as well as many others to whom I have shown them? Now,
perhaps, is the time to revive the well-nigh withered hopes of those
who, guided by more profound contemplations, have discovered the fallacy
of the new observations, and demonstrated the utter impossibility of
their existence. I do not know what to say in a case so surprising, so
unlooked-for, and so novel. The shortness of the time, the unexpected
nature of the event, the weakness of my understanding, and the fear of
being mistaken, have greatly confounded me.' After a certain interval
those bodies reappeared; but Galileo's glass was not sufficiently
powerful to enable him to ascertain their nature nor solve the mystery,
which for upwards of half a century perplexed the ablest astronomers.
The elucidation of this inexplicable phenomenon was reserved for
Christian Huygens, who, with an improved telescope of his own
construction, was able to declare that Saturn's appendages were portions
of a ring which surrounds the planet, and is everywhere distinct from
its surface.
Galileo next directed his attention to the planet Venus, and as a result
of his observations was led to communicate to the public another
anagram:--
Haec immatura a me jam frustra leguntur oy.
This, when rendered correctly, reads:--
Cynthiae figuras aemulatur mater amorum.
Venus rivals the appearances of the Moon.
The phases of Venus were one of the most interesting of Galileo's
discoveries with the telescope. When observed near inferior conjunction
the planet presents the appearance of a slender crescent, resembling
the Moon when a few days old. Travelling from this point to superior
conjunction, the illumined portion of her disc gradually increases,
until it becomes circular, like the full Moon. This changing appearance
of Venus afforded Galileo irresistible proof that the planet is an
opaque body, which derives its light from the Sun, and that it circles
round the orb--convincing evidence of the accuracy and truthfulness of
the Copernican theory.
It was in this manner that Galileo announced his discovery of the phases
of Venus, the peerless planet of our morning and evening skies, whose
slender crescent forms such a beautiful object in the telescope, and
who, as she traverses her orbit, exhibits all the varied changes of form
presented by the Moon in her monthly journey round the Earth. These
varying aspects of Venus were not unknown to Milton; and, indeed, he may
have been informed of them by Galileo in his conversation with him at
Arcetri; nor has he failed to introduce an allusion to this beautiful
phenomenon in his poem. In his description of the Creation, after the
Sun was formed, he adds:--
Hither, as to their fountain, other stars
Repairing, in their golden urns draw light,
And hence the morning planet gilds her horns.--vii. 364-66.
Galileo also discovered that the planet Mars does not always present the
appearance of a circular disc. When near opposition the full disc of the
planet is visible, but at all other times it is gibbous, and approaches
nearest to that of a half-moon when at the quadratures.
In the year 1610, on directing his telescope to the Sun, Galileo
detected dark spots on the solar disc. Similar spots, sufficiently large
to be distinguished by the naked eye, had been observed from time to
time for centuries prior to the invention of the telescope, but nothing
was known of their nature. In 1609 Kepler observed a spot on the Sun,
which he thought was the planet Mercury in conjunction with the orb; the
short time during which it was visible, in consequence of clouds having
obscured the face of the luminary, prevented him from being able to
determine the accuracy of his surmise, but since then it has been
ascertained that no transit of Mercury took place at that time, and
Kepler afterwards acknowledged that he had arrived at an erroneous
conclusion. Galileo was much puzzled in trying to find out the true
nature of the spots. At first he was led to imagine that planets like
Mercury and Venus revolved round the Sun at a short distance from the
orb, and that their dark bodies, travelling across the solar disc, gave
rise to the phenomenon of the spots. After further observation, he
ascertained that the spots were in actual contact with the Sun; that
they were irregular in shape and size, and continued to appear and
disappear. Sometimes a large spot would break up into several smaller
ones, and at other times three or four small spots would unite to form a
large one. They all had a common motion, and appeared to rotate with
the Sun, from which Galileo concluded that the orb rotated on his axis
in about twenty-eight days. Galileo believed that the spots were clouds
floating in the solar atmosphere, and that they intercepted a portion of
the light of the Sun.
The Milky Way, that wondrous zone of light which encircles the heavens,
remained for many ages a source of perplexity to ancient astronomers and
philosophers, who, in their endeavours to ascertain its nature, had
arrived at various absurd and erroneous conclusions. On directing his
telescope to this luminous tract, Galileo discovered, to his
inexpressible admiration, that it consists of a vast multitude of stars,
too minute to be visible to the naked eye. He also discerned that its
milky luminosity is created by the blended light of myriads of stars, so
remote as to be incapable of definition by his telescope. In his
'Nuncius Sidereus' he gives an account of his observations of the Galaxy
and expresses his satisfaction that he has been enabled to terminate an
ancient controversy by demonstrating to the senses the stellar structure
of the Milky Way. When engaged in exploring the celestial regions with
his telescope, Galileo observed a marked difference in the appearance of
the fixed stars, as compared with that of the planets. Each of the
latter showed a rounded disc resembling that of a small moon, but the
stars exhibited no disc, and shone as vivid sparkling points of light;
all of them, whether of large or small magnitude, presenting the same
appearance in the telescope. This led him to conclude that the fixed
stars were not illumined by the Sun, because their brilliancy in all
their changes of position remained unaltered. But, in the case of the
planets, he found that their lustre varied according to their distance
from the Sun; consequently, he believed they were opaque bodies which
reflected the solar rays. On directing his telescope to the Pleiades,
which, to the naked eye, appear as a group of seven stars, he succeeded
in counting forty lucid points. The nebula Praesepe in Cancer, he was
also able to resolve into a cluster of stars. Galileo made many other
observations of the heavenly bodies with his telescope, all of which he
describes as having afforded him 'incredible delight.'
Shortly before the failure of his eyesight, Galileo discovered the
Moon's diurnal libration, a variation in the visible edges of the Moon
caused by its oscillatory motion, and the diurnal rotation of the Earth
on her axis.
Though Milton has not favoured us with any interesting details of his
interview with Galileo, nor expressed his opinions with regard to the
controversies which at that time agitated both the religious and
scientific worlds of thought, and which eventually culminated in a storm
of rancour and hatred that burst over the devoted head of the aged
astronomer, and brought him to his knees, yet he informs us that he
'found and visited' Galileo, whom he describes as 'grown old,' and
cynically remarks that he 'was held a prisoner of the Inquisition for
thinking in astronomy otherwise than the Franciscan and Dominican
licensers thought.' Milton does not allude to his blindness, and yet it
would be natural to imagine that, had his host suffered from this
affliction at the time of his visit, he would have referred to it. We
learn that Milton arrived in Italy in the spring of 1638. In 1637, the
affection which, in the preceding year, deprived Galileo of the use of
his right eye, attacked the left also, which began to grow dim, and in
the course of a few months became sightless; so that, although Milton
has not alluded to this calamity, Galileo had become totally blind at
the time of his visit.
How much Milton was impressed with the fame of Galileo and his telescope
becomes apparent on referring to his 'Paradise Lost.' In it he alludes
to the instrument upon three different occasions, twice when in the
hands of Galileo; and the remembrance of the same artist was doubtless
in his mind when he mentions the 'glazed optic tube' in another part of
his poem. The interval that elapsed from the date of Milton's visit to
Galileo in 1638, to the publication of 'Paradise Lost' in 1667, included
a period of about thirty years, yet this length of time did not erase
from Milton's memory his recollection of Galileo and of his pleasant
sojourn at Florence.
The first allusion in the poem to the Italian astronomer is in the lines
in which Milton describes the shield carried by Satan:--
The broad circumference
Hung on his shoulders like the Moon, whose orb
Through optic glass the Tuscan artist views
At evening, from the top of Fesole,
Or in Valdarno, to descry new lands,
Rivers, or mountains, in her spotty globe.--i. 286-91.
Galileo is described as having observed the Moon from the heights of
Fesole, which formed part of the suburbs of Florence, or from Valdarno,
the valley of the Arno, in which the city is situated. The belief that
Galileo had discovered continents and seas on the Moon justified Milton
in imagining the existence of rivers and mountains on the lunar surface.
The expression 'spotty globe' is more descriptive of the appearance of
our satellite when observed with the telescope, than when seen with the
naked eye. Galileo's attention was attracted by the freckled aspect of
the Moon--a visual effect created by the number of extinct volcanoes
scattered over the surface of the orb.
In his next allusion to the telescope Milton associates Galileo's name
with the instrument:--
As when by night the glass
Of Galileo, less assured, observes
Imagined lands and regions in the Moon.--v. 261-63.
In these lines Milton describes with accuracy the extent of Galileo's
knowledge of our satellite. The conclusions which the Italian astronomer
arrived at with regard to its habitability were not supported by
telescopic evidence sufficient to justify such a belief. Galileo writes:
'Had its surface been absolutely smooth it would have been but a vast,
unblessed desert, void of animals, of plants, of cities and men; the
abode of silence and inaction--senseless, lifeless, soulless, and
stripped of all those ornaments which now render it so variable and so
beautiful:'--
There lands the Fiend, a spot like which perhaps
Astronomer in the Sun's lucent orb
Through his glazed optic tube yet never saw.--iii. 588-90.
Milton may have remembered that Galileo was the first astronomer who
directed a telescope to the Sun; and that he discovered the dark spots
frequently seen on the solar disc.
Anyone who has read a history of the life of Galileo, and contemplated
the career of this remarkable man, his ardent struggles in the cause of
freedom and philosophic truth, his victories and reverses, his brilliant
astronomical discoveries, and his investigation of the laws of motion,
and other natural phenomena, will arrive at the conclusion that he
merited the distinction conferred upon him by our great English poet,
when he included him among the renowned few whose names are found in the
pages of 'Paradise Lost.'