The opinion that our World, or universe, is not the only one in the
Whole, is attributed, in general terms, to many of the early Greek
philosophers, notably to Anaximander. The exact meaning of a ‘Cosmos’,
in this connexion, is perhaps not easy to fix. Aristotle is clear that
the circle of the fixed stars is one and constant, but the author of the
Stoical treatise on the Cosmos, found among his works, takes stars to be
a part of the (one) Cosmos. An earth, such as ours with her atmosphere
and moon, is essential, and a sun, or access to sunlight, and perhaps
some planets. In the _Dream of Scipio_ our solar system, with the earth
in its centre, is described with great distinctness as a unit in space.
The planets are always regarded as luminous points, stars somewhat out
of place (see p. 268), possessing no definite magnitude or solid
substance.
In theory the number of Cosmi might be infinite, but a shrinking from
the vague ‘Infinity’, in later times associated with the Epicureans, led
Plato, for instance, to restrict the number to a possible five. That he
based this number upon that of the five regular solids may seem
fanciful, but the solid angles and forms observed in crystals might
reasonably suggest the hypothesis that the ultimate constituents of the
crust of the earth would be found in the most perfect solid structures
known to theory. In theory there is much that is attractive in these
five solids. To one coming fresh from a study of Plane Polygonal
Figures, which exist in infinite number, and, when regular, approximate
more and more closely to the Plane Circle, it comes as a surprise to
find that, in the next higher degree, the number of solid bodies so
approximating to the Sphere is five only. Again, it seems almost a
paradox that, of these five, the nearest approximation to the Sphere is
attained, not by the body with twenty fine faces, but by that which
shews only twelve, and those comparatively blunted and unshapely
(pentagons). It was perhaps from such considerations that the
Dodecahedron was held of special importance by the Pythagoreans. Plato’s
study of the several faces of these solids, as available for
construction or reconstruction of a world, leaves nothing to be desired,
assuming that a solid body can be built out of plane figures, an
assumption which appears to belong to the same habit of thought as that
which makes the point the square of unity, and the lineal measure
corresponding to the number two the first rectangle. As the pentagon
defies the analysis available for the equilateral triangle or for the
square, the Dodecahedron remains over, a model or pattern of a
stitch-work world, as viewed from outside (_Phaedo_ 110 B and _Timaeus_
55 C; see also Burnet’s _Early Greek Philosophy_, p. 341 foll.). It may
not be amiss to be reminded that Kepler, mathematician as well as
astronomer, spent many toilsome years in the endeavour to arrange the
members of our solar system upon a plan based on the five solids. ‘If
Kepler went out “to seek his father’s asses”, he found a kingdom, for it
was in the course of these speculations, and through them, that he
discovered not only his own “Third Law”, but also the truth, overlooked
by Copernicus, that the orbit of each planet lies in a plane which
passes through the centre of the sun.’ (Dreyer, _Planetary Systems_, p.
410.)
The discussion of the plurality of worlds, in the modern sense, begins
with the very attractive work of Fontenelle, brought out, in its
original form, in 1686, a year before Newton’s _Principia_, being a
series of conversations between the Author and a witty and accomplished
Marquise, as to the habitability of the several members of the solar
system. The argument which followed is distinguished by many great
names, those of Newton himself, Bentley, Huyghens, the Herschels, Dr.
Chalmers, till it was brought to a head in the middle of the nineteenth
century by Dr. Whewell and Sir David Brewster, writing respectively
against and for the hypothesis. The subject was then one (as readers of
Anthony Trollope will remember) upon which any one might be called upon
to take a side in a London drawing-room. In more recent times interest
has been concentrated upon Mars, who now possesses the distinction of
having two satellites. We are only concerned to invite the reader to
compare the religious argument addressed to the Stoics by Plutarch (p.
142 foll.) with the religious argument drawn by Dr. Chalmers and Sir
David Brewster from the enrichment of the providential scheme for man
upon our earth which would follow the conception of other earths
tenanted by other beings perhaps of a higher order.
But it is natural that any such speculation should begin with the moon,
and in fact we find the question of her habitability discussed by Theon
and by Lamprias (pp. 293-9). With the later treatises on this subject,
beginning with Lucian’s witty flight of fancy, we are not concerned. But
an exception must be made for the very able works of Savinien de Cyrano,
known to us as Cyrano de Bergerac, whose _Histoire comique des États et
Empires de la Lune_ appeared, probably, in 1650, and was followed by a
similar work about the sun. Cyrano appears to be familiar with Plutarch:
thus he meets in the moon the ‘daemon of Socrates’, who has also been
the tutelary spirit of Epaminondas, of Cato of Utica, and of Brutus. The
idea (due in the first place to Heraclitus) of being fed on smells, is
worked out with much vivacity. But with so original and daring a writer,
it is not quite easy to settle how much is due to any hint from others
and how much to himself. A modern reader will not need to be reminded
that Cyrano was not a person of whom it was wise to give an outspoken
opinion in his lifetime. But I had wished to speak with nothing but
respect of a man of real learning and genius, who, from whatever cause,
did not bring to perfection any work worthy of himself.
See, on the general subject, an Essay by the late Professor Henry J. S.
Smith in _Oxford Essays_, 1855.
INDEX
OF PERSONS AND PLACES MENTIONED BY PLUTARCH IN THESE DIALOGUES
¶ In this Index the Greek spelling of ei (Lat. ī) has been usually
retained.
All dates are B. C. unless otherwise stated.
The dates are often approximate and conventional.
Other numerals refer to pages of this volume.
For the speakers in each Dialogue see that Dialogue _passim_ and the
Introductions.
(The ‘Three Pythian Dialogues’ are quoted under that designation See p.
52.)