On Generation and corruption   

(i) if all of them are uniform in substance, what is it that separated

one from another? Or why, when they come into contact, do they not

coalesce into one, as drops of water run together when drop touches

drop (for the two cases are precisely parallel)? On the other hand

(ii) if they fall into differing sets, how are these characterized? It

is clear, too, that these, rather than the 'figures', ought to be

postulated as 'original reals', i.e. causes from which the phenomena

result. Moreover, if they differed in substance, they would both act

and suffer action on coming into reciprocal contact.

V. Again, what is it which sets them moving? For if their 'mover' is

other than themselves, they are such as to 'suffer action'. If, on the

other hand, each of them sets itself in motion, either (a) it will

be divisible ('imparting motion' qua this, 'being moved' qua that), or

(b) contrary properties will attach to it in the same respect-i.e.

'matter' will be identical in-potentiality as well as

numerically-identical.

As to the thinkers who explain modification of property through

the movement facilitated by the pores, if this is supposed to occur

notwithstanding the fact that the pores are filled, their postulate of

pores is superfluous. For if the whole body suffers action under these

conditions, it would suffer action in the same way even if it had no

pores but were just its own continuous self. Moreover, how can their

account of 'vision through a medium' be correct? It is impossible

for (the visual ray) to penetrate the transparent bodies at their

'contacts'; and impossible for it to pass through their pores if every

pore be full. For how will that differ from having no pores at all?

The body will be uniformly 'full' throughout. But, further, even if

these passages, though they must contain bodies, are 'void', the

same consequence will follow once more. And if they are 'too minute to

admit any body', it is absurd to suppose there is a 'minute' void

and yet to deny the existence of a 'big' one (no matter how small

the 'big' may be), or to imagine 'the void' means anything else than a