THE DISSOLUTION OF THE OLD SYNTHESIS
We have seen that there are classic religious periods when faith and
knowledge have seemed to approximate to one another. The Middle Ages in
Europe constituted such a period; no "Religion _v._ Science" controversy
could then be said to exist; the best scientific knowledge of the time
seemed to sanction the popular religious notions. Learned and lay
thought in the same terms; the wolf lay down with the lamb.
THE OLD WORLD-SCHEME.--It is important to grasp the main features of a
world-scheme which as late as the fifteenth century passed everywhere
without criticism.
The father of it was Aristotle. His conception of the universe rested
upon the plain contrast, which strikes the unsophisticated observer,
between the unembarrassed and regular movements of the heavenly bodies
and the disordered agitations of sublunary things. Hence the heavenly
region was eternal, and the region of earth transitory: yonder, the
motions that take place are eternal and regular; here, motion and rest
alternate, nothing "continueth in one stay."
At the centre of the universe stands Earth: hence we mount through three
sublunary strata to the region of the celestial ether, which is purer
as distance from the Earth increases.
These strata form three concentric "spheres" which, solid yet
transparent (like crystal), revolve around the earth. The first contains
the moon--like a fly in amber; the second, the sun; the third, the fixed
stars; which last sphere is also the first of several successive
heavens, the highest of which is the seat of Deity.
This Aristotelio-Ptolemaic system[2] formed a coherent framework for
biblical world-notions. Here too, earth stands still while sun and stars
revolve; here, too, the seat of Deity is the highest heaven. This was an
universe where men could feel their feet on firm ground; their minds
found rest in those simple and definite notions which make religious
conceptions easy to understand and accept; their imaginations were not
yet disturbed and disquieted by thoughts of space and time without end
and without beginning.
AQUINAS.--Such was the "world of nature," the theatre for that "world of
grace" which Revelation spoke of, and which led eventually to the
eternal "world of glory" in which the faithful should have their
portion. _Natura_, _gratia_, _gloria_ was the ascending series (like
another set of celestial spheres), and the whole economy was elaborated
into a logical system, known to the historians of thought as
Scholasticism: a philosophy which found its most perfect and memorable
expression in Thomas Aquinas (1227-74), the _doctor angelicus_ of
Catholic theology, canonised less than fifty years after his death. The
_Summa Philosophica_, where Aquinas deals with the rational foundations
of a Christian Theism, and the _Summa Theologica_, where he erects his
elaborate structure of theology and ethics, together constitute "one of
the most magnificent monuments of the human intellect, dwarfing all
other bodies of theology into insignificance."[3] In him the erudition
of an epoch found its spokesman; he was the personification of an
intellectual ideal. To his contemporaries he stood beyond the range of
criticism. In the _Paradiso_ (x.8.2) it is St. Thomas who speaks in
heaven.
Nevertheless, the Scholastic world-scheme, though based on "the evidence
of the senses, the investigations of antiquity, and the authority of the
Church," and though Aquinas had set the seal of finality upon it, was
destined to gradual discredit and ultimate extinction.
DISINTEGRATION BEGINS.--It was open to attack on two sides. _Either_
observations or calculations might be brought forward, conflicting with
it, or making another conception possible or probable: _Or_ the validity
of conventional ideas of space might be disputed.
The latter type of criticism was the first to occur. Nicholas Cusanus
(1401-1464), an inhabitant of the Low Countries, subsequently bishop and
cardinal, developed unconventional notions about Space. He suggested
that wherever man finds himself--on earth, sun, or star--he will always
regard himself as standing at the centre of existence. There is, in
fact, no point in the universe which might not appropriately be called
its centre, and to say that the earth stands at the centre is only (what
we should now call it) an anthropomorphism. So much for _place_; and
similarly with _motion_. Here, too, there is no absolute standard to
apply: motion may exist, but be unnoticed if there be no spot at
absolute rest from which to take bearings.
"We are like a man in a boat sailing with the stream, who does not know
that the water is flowing, and who cannot see the banks: how is he to
discover whether the boat is moving?" Cusanus, in fact, denies the
fundamental Aristotelian dogma that the earth is the central point of
the universe, because, on general grounds, there _can_ be no absolute
central point. This gave a shock to the "geocentric theory" from which
it never recovered.
Worse shocks, however, were to come. The name of the man who actually
(as Luther complained) turned the world upside down, is notorious
enough. Poles and Germans alike have claimed the nationality of Nicolaus
Copernicus (1473-1543); who, having been a student at Cracow and in
Italy, became a prebendary in Frauenburg Cathedral.
THE NEW ASTRONOMY.--The general criticisms of Cusanus were elaborated by
Copernicus. The senses cannot inform us (when any motion takes place)
_what_ it is that moves. It may be the thing perceived that moves, or
the percipient--or both. And it would be _possible_ to account for the
movements of celestial bodies by the supposition that it is the earth
that moves, and not they. Copernicus' whole work consisted in the
mathematical demonstration that this hypothesis could account for the
phenomena as we observe them. In fact, when these demonstrations were
eventually published (it was only on his death-bed that Copernicus
received a copy of his book--and he had already lost consciousness) they
were introduced by a discreet preface, which intimated that the whole
thing might safely be regarded as a _jeu d'esprit_ on the part of an
eccentric mathematician. And this editorial _caveto_, though written by
another hand, preserved the Copernican theories from the notoriety that
might otherwise have attended, and afterwards did attend, them.
Copernican conceptions were semi-traditional. The sun displaces the
earth as the central point of the universe: around it revolve the
planets--including the earth; and, at an immeasurable distance, is the
immovable heaven of the fixed stars. Copernicus left it an open question
whether or no the universe was infinite. It remained for his successor,
the greatest of the Renaissance thinkers, Giordano Bruno (1548-1600) to
declare it to be limitless, and to contain an infinity of worlds like
our own. The fixed stars became, for him, suns surrounded by planets.
The traditional distinction between the celestial and sublunary spheres
had vanished. The bewilderment and indignation excited by these ideas,
revolting to the conscience of his time, cost their author his life.
GALILEO.--The criticism of the old world-conceptions was, however, to be
based on yet more sure ground by one who relied, not on general
considerations, but on observation and experiment. Galileo (1564-1642)
studied philosophy, physics, and mathematics at Pisa; and as professor
expounded the old astronomy long after he had ceased to regard it as
adequate. Not until 1610, after he had constructed a telescope and
observed the satellites of Jupiter, did he openly confess his adherence
to the system of Copernicus. The observation of sun-spots and the phases
of Venus confirmed his opinion.
Aristotelian astronomers declined to witness these phenomena through his
telescope, and perhaps Galileo was right in observing with a sigh that
were the stars themselves to descend from heaven to bear him witness his
critics would remain obdurate.[4]
It was not until 1632 that a complete exposition of the conflict between
the two world-systems was produced by Galileo. It took the form of a
dialogue between three speakers--conservative, mediating, and extreme.
The views of the author, however, were not sufficiently concealed, the
book was prohibited, and Galileo summoned to Rome, and upon threat of
torture, subdued into a recantation and a promise not to offend in the
future. That Galileo perjured himself is not open to doubt, nor did he
change his convictions. A subsequent work, surreptitiously printed in
Holland, contained the same heresies expressed with less reserve.
THE NEW PHYSICS.--It might be said, then, that the fabric of the
universe had been reconstructed by the thinkers whose explorations we
have hitherto followed. This achievement, however, though sufficiently
startling in itself, was not the only, and perhaps not the most
important, of their performances. The question still awaited solution:
_By what forces and laws is the new world-system maintained in
activity?_
The traditional reply had been that the universe was kept in motion by
the operation of the Deity. While the truth of this reply was not
questioned by the advocates of the "new" science, it did not seem to
them to dispel the obscurity surrounding certain points about which they
required information. It was Galileo who observed that the appeal to the
divine will explains nothing just because it explains everything. It
takes the inquirer back too far--behind those details of method which
arouse his speculative interest.
This desire to understand those methods of operation which natural
objects appear to follow, led philosophers to enunciate certain "laws"
about them. These served as "explanations" of particular classes of
phenomena. It was the phenomena of _motion_ that especially attracted
their attention; and many ingenious experiments were performed by
Galileo, in particular, which led him to conclusions which then seemed
paradoxical, but now serve as axioms of physical science; for "the laws
of motion contain the key to all scientific knowledge of material
nature." When Galileo, after careful experiment, established the
proposition that a body can neither change its motion of itself, nor
pass from motion to rest, the fundamental "law of inertia"--of such
incalculable importance to the development of modern physics--had been
established.
AN AUTOMATIC UNIVERSE.--A proposition of this kind may not at first seem
to involve important philosophical or theological consequences. But we
only have to consider that it provided a natural explanation of the
continued and untiring motion of the heavenly bodies. It did not, it is
true, explain how that motion arose; but the motion being "given," it
had now been shown how it would, in the absence of obstructions, be
perpetual. In fact, speculations of this kind opened up the way to the
_mechanical_ explanation of nature, a theory which had been already
speculatively held by Leonardo da Vinci, who is already convinced that
"necessity is the eternal bond, the eternal rule of Nature."
SCIENCE AND MATHEMATICS.--It was not only, however, the spectacle of a
system running automatically that suggested to observers a mechanical
theory to explain it. There was also the fact that phenomena were
observed to occur in accordance with certain simple mathematical laws.
Galileo's experiments with falling bodies led him to foreshadow
principles which were afterwards elaborated and fully demonstrated by
Newton, who may be said to have been the first to construct a mechanical
universe. The principle had already been formulated by a contemporary of
Galileo--Johannes Kepler--in the axiom _ubi materia, ibi geometria_.
RESULTS.--The thinkers whose speculations have engaged us were indeed
responsible for creating a revolution in ideas. For a finite universe
whose centre was the earth, and which was kept in motion by the
operation of the Deity, they had substituted the conception of
illimitable space sown with innumerable systems like our own; and had
created the beginning of a mechanical conception of nature.
THE NEW LOGIC.--But it was not only the scientific dogmas of the old
system that had been so rudely overthrown--the very principles upon
which those dogmas rested had been submitted to a destructive criticism.
The new science produced a new logic. This order of events is not
unusual: first, the new scientific discoveries, and then in the wake of
the discoverers, comes the innovating critic who systematises the
logical or scientific methods to which the new knowledge seems to have
been due. First, Kepler and Galileo, who used the "inductive" method,
and then Lord Bacon of Verulam (1561-1626), who discovered the inductive
logic, and established it as a system.
FRANCIS BACON.--Bacon's doctrine may be summarised by his own epigram,
"If a man begin with certainties, he shall end in doubts; but if he be
content to begin with doubts, he shall end in certainties." Which is
really a criticism of what is known as the a priori method, whereby the
inquirer starts with certain predefined theories to which all phenomena
must conform, and which all experience must verify. If facts will not
suit the particular theory, so much the worse for the facts: one could
always disregard them, and apply a blind eye to Galileo's telescope.
Such is always the procedure of the dogmatic mind, which is already so
certain of the truth of its notions that no evidence can persuade it to
the contrary. But it is not by such means that knowledge is advanced,
and it was for a reversal of these that Bacon pleaded.
Leonardo da Vinci had already anticipated the Baconian logic (which did
not wait for Bacon until it was applied) when he laid down the
proposition that wisdom was the daughter of experience, and rejected all
speculations which experience, the common mother of all sciences, could
not confirm. Hence, knowledge was the product of time; the process of
collecting material for a judgment must often be slow, but the results
were worth the labour--these would not be speculative, but true. Nor
need it be supposed that Bacon excluded imagination from playing a part
in increasing knowledge, he did not plead _only_ for a mechanical
collection of material. It is imagination which in face of abundant
material creates the hypothesis which accounts for it being what it is.
And he was prepared to admit the value of preliminary hypotheses which
might be replaced as further facts were collected, or as insight became
more clear. Here, too, Bacon describes the method followed by modern
science.
PRESTIGE OF NEW METHODS.--And so, by the time when Bacon had laid down
his pen after writing the _New Logic_, the work of discrediting the old
system, elaborated with such ingenious industry by Aquinas, was
tolerably complete. The new science had begun already to be fruitful in
results, both practical and speculative. The successors of Galileo and
of Bacon applied the new principles with vigour, and reached astonishing
results. Justified by these, the new methods secured a prestige which
has not decreased for three centuries.