Speaking 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 had tried to explain multiplicity and motion, they had not broken so radically as Leukippos with the Parmenidean One. Both started with a condition 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 account for their coming together, and there was nothing so far to prevent his return to the old idea that motion does not require any explanation at all.[1]
This, then, is what seems to follow from the criticisms of Aristotle and from the nature of the case; but 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. This 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 now consider whether and in what sense weight is a property of the atoms.
179.The weight of the atoms. As is well known, Epicurus held that the atoms were naturally heavy, and therefore fell continually 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.[2] On the
- ↑ Introd. § VIII.
- ↑ Aet. i. 3, 18 (of Epicurus), συμβεβηκέναι δὲ τοῖς σώμασι τρία ταῦτα, σχῆμα, μέγεθος, βάρος. Δημόκριτος μὲν γὰρ ἔλεγε δύο, μέγεθός τε καὶ σχῆμα, ὁ δὲ Ἐπίκουρος τούτοις καὶ τρίτον βάρος προσέθηκεν· ἀνάγκη γάρ, φησί, κινεῖσθαι, τὰ σώματα τῇ τοῦ βάρους πληγῇ· ἐπεὶ ("or else") οὐ κινηθήσεται;
