Chalk and Flint Formation. 21 



are resolved into these. Moreover that the worlds 

 are formed in this way. That many bodies of all 

 sorts, segregated from the infinite expanse, are 

 carried into void space, and, when collected together, 

 form one vortex of rotation, in which, by colliding 

 while circling round together in all their multi- 

 fariousness, they become separated and assorted like 

 to like. But when, from their multitude, they could 

 no longer be carried round in equipoise, the finer 

 and lighter go off into the outer space as if they 

 were sifted out ; the rest remain together, and, 

 becoming entangled, run together with one another, 

 and form, first, a sort of spherical arrangement. 

 That this spherical shape, like the envelope of an 

 embryo world, 4 including in itself all sorts of bodies, 

 serves as a substratum ; and, having its motion 

 rotatory in consequence of the counter momentum 

 at its centre, the superficial skin or envelope (so to 

 speak) becomes stretched and enlarged, as contiguous 

 bodies, impinging upon the vortex of its revolution, 

 flow together to it. That the earth was formed in 

 this way, those things remaining with it which were 

 carried into the midst ; and that, again, the spherical 

 surface itself, as it were the enclosing skin or 

 membrane [in modern phrase, crust], is thus enlarged 

 by the continual acquisition of bodies from without, 

 which it acquires by impinging on them in the range 

 of its revolution." 5 



4 Olov vfxiva. Alii r/xevas vocant membranas quibus foetus 

 includuntur. — Scapula. The meaning of the passage has been 

 liable to be much misapprehended from neglecting the force of the 

 metaphor. 



5 Diog. Laert. ix. 30 — 33. Muelleri Fragm. Historic. Graec. iv. 

 168, 41. The Greek of the above fragment of Leucippus is as 

 follows : — 



A€UKi7T7ros 6 'EAeaT^s IXeycv t?)v yrjv o^daOat Trepl to 



