On Generation and corruption   

properties, the properties in question being opposed to one another

either as contraries or as intermediates. The body, e.g. although

persisting as the same body, is now healthy and now ill; and the

bronze is now spherical and at another time angular, and yet remains

the same bronze. But when nothing perceptible persists in its identity

as a substratum, and the thing changes as a whole (when e.g. the

seed as a whole is converted into blood, or water into air, or air

as a whole into water), such an occurrence is no longer

'alteration'. It is a coming-to-be of one substance and a passing-away

of the other-especially if the change proceeds from an imperceptible

something to something perceptible (either to touch or to all the

senses), as when water comes-to-be out of, or passes-away into, air:

for air is pretty well imperceptible. If, however, in such cases,

any property (being one of a pair of contraries) persists, in the

thing that has come-to-be, the same as it was in the thing which has

passedaway-if, e.g. when water comes-to-be out of air, both are

transparent or cold-the second thing, into which the first changes,

must not be a property of this persistent identical something.

Otherwise the change will be 'alteration.' Suppose, e.g. that the

musical man passed-away and an unmusical man came-tobe, and that the

man persists as something identical. Now, if 'musicalness and

unmusicalness' had not been a property essentially inhering in man,

these changes would have been a coming-to-be of unmusicalness and a

passing-away of musicalness: but in fact 'musicalness and

unmusicalness' are a property of the persistent identity, viz. man.

(Hence, as regards man, these changes are 'modifications'; though,

as regards musical man and unmusical man, they are a passing-away

and a coming-to-be.) Consequently such changes are 'alteration.'

When the change from contrary to contrary is in quantity, it is

'growth and diminution'; when it is in place, it is 'motion'; when

it is in property, i.e. in quality, it is 'alteration': but, when

nothing persists, of which the resultant is a property (or an