outermost, that of the moon is nearest to the earth, and those of the others are between these. And all the heavenly bodies are ignited because of the swiftness of their motion; while
the sun is also ignited by the stars. But the moon only
receives a small portion of fire. The sun and the moon are eclipsed . . . (And the obliquity of the zodiac is produced) by the earth being inclined towards the south; and the northern parts of it have constant snow and are cold and frozen. And the sun is eclipsed rarely, and the moon con- tinually, because their circles are unequal. And just as there are comings into being of the world, so there are growths and
decays and passings away in virtue of a certain necessity, of
the nature of which he gives no clear account.
As it comes substantially from Theophrastos, this
passage is to be regarded as good evidence for the
cosmology of Leukippos, and it is confirmed in an
interesting way by certain Epicurean extracts from
the Great Diakosmos.' These, however, as is natural,
give a specially Epicurean turn to some of the
doctrines, and must therefore be used with caution.
177. The general impression which we get from the cosmology of Leukippos is that he either ignored
1 These are to be found in Aet. i. 4 (Dox. p. 289; Vors. p. 347; Usener, Zpicurea, fr. 308). Epicurus himself in the second epistle (Diog. x, 88; Usener, p. 37, 7) pe ἃ the phrase ἀποτομὴν ἔχουσα ἀπὸ τοῦ ἀπείρου. ra
Relation
to Tonic
cosmology.
The eternal motion.
392 Early Greek Philosophy
or had never heard of the great advance in the general
view of the world which was due to the later Pytha-
goreans. He is as reactionary in his detailed cos-
mology as he was daring in his general physical theory.
We seem to be reading once more of the speculations
of Anaximenes or even of Anaximander, though there
are traces of Empedokles and Anaxagoras too. The
explanation is not hard to see. Leukippos would not
learn a cosmology from his Eleatic teachers ; and, even
when he found it possible to construct one without
giving up the Parmenidean view of reality, he was
necessarily thrown back upon the older systems of
Ionia. The result was unfortunate. The astronomy
of Demokritos, so far as we know it, was still of this
childish character. There is no reason to doubt the
statement of Seneca that he did not venture to say
how many planets there were.’
This, I take it, is what gives plausibility to Gomperz’s
statement that Atomism was “ the ripe fruit on the tree
of the old Ionic doctrine of matter which had been
tended by the Ionian physiologists.”? The detailed
cosmology was certainly such a fruit, and it was
possibly over-ripe; but the atomic theory proper, in
which the real greatness of Leukippos comes out, was
wholly Eleatic in its origin. Nevertheless, it will repay
us to examine the cosmology too; for such an examina-
tion will serve better than anything else to bring out
the true nature of the historical development of which
it was the outcome.
178. Leukippos represented the atoms as having been always in motion. Aristotle puts this in his own
1 Seneca, Q. Wat. vii. 3. 2 Gomperz, Greek Thinkers, vol. i. p. 323.
Ss ee ee. ee oe ee ee ᾿ ὮΝ a ire
Leukippos of Miletos 393
way. The atomists, he says, “indolently” left it un-
explained what was the source of motion, and they
did not say what sort of motion it was. In other
words, they did not decide whether it was a “natural
motion” or one impressed on them “contrary to their
nature.”’ He even went so far as to say that they
made it “ spontaneous,” a remark which has given rise
to the erroneous view that they held it was due to
chance.” Aristotle does not say that, however; but
only that the atomists did not explain the motion of
the atoms in any of the ways in which he himself
explained the motion of the elements. They neither
ascribed to them a natural motion like the circular
motion of the heavens and the rectilinear motion of
the four elements in the sublunary region, nor did they
give them a forced motion contrary to their own nature,
like the upward motion which may be given to the
heavy elements and the downward which may be
given to the light. The only fragment of Leukippos
which has survived is an express denial of chance.
“Naught happens for nothing,” he said, “but evéry-
thing from a ground and of necessity.” *
If we put the matter historically, all this means that
Leukippos did not, like Empedokles and Anaxagoras,
find it necessary to assume a force to originate motion.
He had no need of Love and Strife or Mind, and the
reason is clear. Though Empedokles and Anaxagoras
1 Arist. Phys. ©, 1. 252 a 32 (R. P. 195 a); de Caelo, T, 2. 300 Ὁ 8 (R. P. 195); Aer. A, 4. 985 Ὁ 19 (R. P. 22.).
2 Arist. Phys, B, 4. 196 a 24 (R. P. 195d). Cicero, de nat, D. i. 66 (R. P. 2.). The latter passage is the source of the phrase ‘‘ fortuitous concourse” (concurrere = συντρέχειν).
3 Aet. i. 25, 4 (Dox. p. 321), Λεύκιππος πάντα κατ᾽ ἀνάγκην, τὴν δ᾽ αὐτὴν ὑπάρχειν εἱμαρμένην. λέγει γὰρ ἐν τῷ Περὶ νοῦ" Οὐδὲν χρῆμα μάτην γίγνεται, ἀλλὰ πάντα ἐκ λόγου τε καὶ ὑπ᾽ ἀνάγκης.
The weight of the atoms.
394. Early Greek Philosophy
had tried to explain multiplicity and motion, they had
not broken so radically as Leukippos did with the
Parmenidean One. Both of them started with a con-
dition of matter in which the “roots” or “seeds” were
mixed so as to be “all together,” and they therefore
required something to break up this unity. Leukippos,
who started with an infinite number of Parmenidean
“Ones,” so to speak, required no external agency to
separate them. What he had to do was just the
opposite. He had to give an explanation of their
coming together, and there was nothing so far to
prevent his return to the old and natural idea that
motion does not require any explanation at all.’
This, then, is what seems to follow from the
criticisms of Aristotle and from the nature of the
case ; but it will be observed that it is not consistent
with Zeller’s opinion that the original motion of the
atoms is a fall through infinite space, as in the system
of Epicurus. Zeller’s view depends, of course, on the
further belief that the atoms have weight, and that
weight is the tendency of bodies to fall, so we must
go on to consider whether and in what sense weight
is a property of the atoms.
179. As is well known, Epicurus held that the
atoms were naturally heavy, and therefore fell con-
tinually in the infinite void. The school tradition is,
however, that the “natural weight” of the atoms was
an addition made by Epicurus himself to the original
atomic system. Demokritos, we are told, assigned two
properties to atoms, magnitude and form, to which
Epicurus added a third, weight.” On the other hand,
1 Introd. § ΝΠ. 2 Aet. 1. 3, 18 (of Epicurus), συμβεβηκέναι δὲ τοῖς σώμασι τρία ταῦτα, σχῆμα, μέγεθος, βάρος. Δημόκριτος μὲν yap ἔλεγε δύο, μέγεθός τε καὶ
Leukippos of Miletos 395
Aristotle distinctly says in one place that Demokritos
held the atoms were heavier “in proportion to their
excess,” and this seems to be explained by the state-
ment of Theophrastos that, according to him, weight
depended on magnitude.’ It will be observed that,
even so, it is not represented as a primary property of
the atoms in the same sense as magnitude.
It is impossible to solve this apparent contradiction
without referring briefly to the history of Greek ideas
about weight. It is clear that lightness and weight
would be among the very first properties of body to
bé distinctly recognised as such. The necessity of
lifting burdens must very soon have led men to
distinguish them, though no doubt in some primitive
and more or less animistic form. Both weight and
lightness would be thought of as ¢hings that were im
bodies. Now it is a remarkable feature of early Greek
philosophy that from the first it was able to shake
itself free from this idea. Weight is never spoken of
as a “thing” as, for instance, warmth and cold are;
and, so far as we can see, not one of the thinkers we
σχῆμα, ὁ δὲ ᾿Επίκουρος τούτοις καὶ τρίτον βάρος προσέθηκεν " ἀνάγκη γάρ, φησί, κινεῖσθαι τὰ σώματα τῇ τοῦ βάρους πληγῇ ἐπεὶ (‘* or else”) οὐ κινηθή- σεται; 16. 12, 6, Δημόκριτος “τὰ πρῶτά φησι σώματα, ταῦτα δ᾽ ἣν τὰ ναστά, βάρος μὲν οὐκ ἔχειν, κινεῖσθαι δὲ κατ᾽ ἀλληλοτυπίαν ἐν τῷ ἀπείρῳ. Cic. de fato, 20, ‘vim motus habebant (atomi) a Democrito impulsionis quam plagam ille appellat, a te, Epicure, gravitatis et ponderis.” These passages represent the Epicurean school tradition, which would hardly venture to misrepresent Demokritos on so important a point. His works were still accessible. It is confirmed by the Academic tradition in de Fin. i. 17 that Demokritos taught the atoms moved ‘‘in infinito inani, in quo nihil nec summum nec infimum nec medium nec extremum sit.” This doctrine, we are od, os ‘* depraved ” by Epicurus.
1 Arist. de Gen. Corr. 326 a 9, καίτοι βαρύτερόν γε κατὰ τὴν ὑπεροχήν φησιν εἶναι Δημόκριτος ἕκαστον τῶν ἀδιαιρέτων. I cannot believe this means anything else than what Theophrastos says in his fragment on sensation, § 61 (R. P. 199), βαρὺ μὲν οὖν καὶ κοῦφον τῷ μεγέθει διαιρεῖ Δημόκριτος.
396 Early Greek Philosophy
have studied hitherto thought it necessary to give any
explanation of it at all, or even to say anything about
it! The motions and resistances which popular theory
ascribes to weight are all explained in some other way.
Aristotle distinctly declares that none of his pre-
decessors had said anything of absolute weight and
lightness. They had only treated of the relatively
light and heavy.’
This way of regarding the popular notions of weight and lightness is clearly formulated for the first time in Plato’s Zimaeus. There is no such thing in the world, we are told there, as “up” or “down.” The middle of the world is not “down” but “just in the middle,” and there is no reason why any point in the circumference should be said to be “above” or “below” another. It is really the tendency of bodies towards their kin that makes us call a falling body heavy and the place to which it falls “below.” Here Plato is really giving the view which was taken more or less consciously by his predecessors, and it is not till the time of Aristotle that it is questioned.* For reasons which do not concern us here, he definitely identified the circumference of
the heavens with “up” and the middle of the world
1 In Aet. i. 12, where the Jlactta regarding the heavy and light are given, no philosopher earlier than Plato is referred to. Parmenides (fr. 8, 59) speaks of the dark element as ἐμβριθές. I do not think that there is any other place where weight is even mentioned in the fragments of the early philosophers.
2 Arist. de Caelo, 308 a 9, περὶ μὲν οὖν τῶν ἁπλῶς λεγομένων (βαρέων καὶ κούφων) οὐδὲν εἴρηται παρὰ τῶν πρότερον.
3 Plato, 77m. 61 c 3 sqq.
4 Zeller says (p. 876) that in antiquity no one ever understood by weight anything else than the property of bodies in virtue of which they move downwards ; except that in such systems as represent all forms of matter as contained in a sphere, ‘‘ above” is identified with the circumference and “below” with the centre. As to that, I can only say that no such theory of weight is to be found in the fragments of the early philosophers or is anywhere ascribed to them, while Plato expressly denies it.
Leukippos of Miletos 397
with “down,” and equipped the four elements with
natural weight and lightness that they might perform
their rectilinear motions between them. As, however,
Aristotle believed there was only one world, and as he
did not ascribe weight to the heavens proper, the effect
of this reactionary theory upon his cosmical system
was not great; it was only when Epicurus tried to
combine it with the infinite void that its true character
emerged. It seems to me that the nightmare of
Epicurean atomism can only be explained on the
assumption that an Aristotelian doctrine was violently
adapted to a theory which really excluded it. It is
totally unlike anything we meet with in earlier days.
This brief historical survey suggests at once that it
is only in the vortex that the atoms acquire weight
and lightness,’ which are, after all, only popular names
for facts which can be further analysed. We are told
that Leukippos held that one effect of the vortex was
that like atoms were brought together with their likes.’
In this way of speaking we seem to see the influence
of Empedokles, though the “likeness” is of another
kind. It is the finer atoms that are forced to the
circumference, while the larger tend to the centre. We