On Generation and corruption   

Plato investigated the conditions under which things come-to-be and

pass-away, he confined his inquiry to these changes; and he

discussed not all coming-to-be, but only that of the elements. He

asked no questions as to how flesh or bones, or any of the other

similar compound things, come-to-be; nor again did he examine the

conditions under which 'alteration' or growth are attributable to

things.

A similar criticism applies to all our predecessors with the

single exception of Democritus. Not one of them penetrated below the

surface or made a thorough examination of a single one of the

problems. Democritus, however, does seem not only to have thought

carefully about all the problems, but also to be distinguished from

the outset by his method. For, as we are saying, none of the other

philosophers made any definite statement about growth, except such

as any amateur might have made. They said that things grow 'by the

accession of like to like', but they did not proceed to explain the

manner of this accession. Nor did they give any account of

'combination': and they neglected almost every single one of the

remaining problems, offering no explanation, e.g. of 'action' or

'passion' how in physical actions one thing acts and the other

undergoes action. Democritus and Leucippus, however, postulate the

'figures', and make 'alteration' and coming-to-be result from them.

They explain coming-to-be and passing-away by their 'dissociation' and

'association', but 'alteration' by their 'grouping' and 'Position'.

And since they thought that the 'truth lay in the appearance, and

the appearances are conflicting and infinitely many, they made the

'figures' infinite in number. Hence-owing to the changes of the

compound-the same thing seems different and conflicting to different

people: it is 'transposed' by a small additional ingredient, and

appears utterly other by the 'transposition' of a single

constituent. For Tragedy and Comedy are both composed of the same

letters.