On Generation and corruption   

change of that kind is not peculiarly distinctive of growth, but

characterizes coming-to-be as such or in general. For growth is an

increase, and diminution is a lessening, of the magnitude which is

there already-that, indeed, is why the growing thing must possess some

magnitude. Hence growth must not be regarded as a process from a

matter without magnitude to an actuality of magnitude: for this

would be a body's coming-to-be rather than its growth.

We must therefore come to closer quarters with the subject of our

inquiry. We must grapple' with it (as it were) from its beginning, and

determine the precise character of the growing and diminishing whose

causes we are investigating.

It is evident (i) that any and every part of the growing thing has

increased, and that similarly in diminution every part has become

smaller: also (ii) that a thing grows by the accession, and diminishes

by the departure, of something. Hence it must grow by the accession

either (a) of something incorporeal or (b) of a body. Now, if (a) it

grows by the accession of something incorporeal, there will exist

separate a void: but (as we have stated before)' is impossible for a

matter of magnitude to exist 'separate'. If, on the other hand (b)

it grows by the accession of a body, there will be two bodies-that

which grows and that which increases it-in the same place: and this

too is impossible.

But neither is it open to us to say that growth or diminution occurs

in the way in which e.g. air is generated from water. For, although

the volume has then become greater, the change will not be growth, but

a coming to-be of the one-viz. of that into which the change is taking

place-and a passing-away of the contrasted body. It is not a growth of

either. Nothing grows in the process; unless indeed there be something

common to both things (to that which is coming-to-be and to that which

passed-away), e.g. 'body', and this grows. The water has not grown,

nor has the air: but the former has passed-away and the latter has

come-to-be, and-if anything has grown-there has been a growth of