Book 10
1.43
The atoms are in continual motion through all eternity. [Further, he says below,Properly further within—a proof that the Scholiast read his Epicurus from a papyrus scroll which had to be unrolled. Hence further within or nearer the centre expresses the same thing as further on or below in a modern book. that the atoms move with equal speed, since the void makes way for the lightest and heaviest alike.] Some of them rebound to a considerable distance from each other, while others merely oscillate in one place when they chance to have got entangled or to be enclosed by a mass of other atoms shaped for entangling.Note the distinction between (1) solids, composed of interlacing atoms (which have got entangled), and (2) fluids, composed of atoms not interlaced, needing a sheath or container of other atoms, if they are to remain united. To (2) belongs Soul (§ 66). See Lucr. ii. 80-141; Cic. De fin. i. 7.
