ome who said that qualities and
immaterial forms are not susceptible of more or less, but that
material forms are.

In order that the truth in this matter be made clear, we must observe
that [that], in respect of which a thing receives its species, must
be something fixed and stationary, and as it were indivisible: for
whatever attains to that thing, is contained under the species, and
whatever recedes from it more or less, belongs to another species,
more or less perfect. Wherefore, the Philosopher says (Metaph. viii,
text. 10) that species of things are like numbers, in which addition
or subtraction changes the species. If, therefore, a form, or
anything at all, receives its specific nature in respect of itself,
or in respect of something belonging to it, it is necessary that,
considered in itself, it be something of a definite nature, which can
be neither more nor less. Such are heat, whiteness or other like
qualities which are not denominated from a relation to something
else: and much more so, substance, which is _per se_ being. But those
things which receive their species from something to which they are
related, can be diversified, in respect of themselves, according to
more or less: and nonetheless they remain in the same species, on
account of the oneness of that to which they are related, and from
which they receive their species. For example, movement is in itself
more intense or more remiss: and yet it remains in the same species,
on account of the oneness of the term by which it is specified. We
may observe the same thing in health; for a body attains to the
nature of health, according as it has a disposition suitable to an
animal's nature, to which various dispositions may be suitable; which
disposition is therefore variable as regards more or less, and withal
the nature of health remains. Whence the Philosopher says (Ethic. x,
2, 3): "Health itself may be more or less: for the measure is not the
same in all, nor is it always the same in one individual; but down to
a certain point it may decrease and still remain health."

Now these various dispositions and measures of health are by way of
excess and defect: wherefore if the name of health were given to the
most perfect measure, then we should not speak of health as greater
or less. Thus therefore it is clear how a quality or form may
increase or decrease of itself, and how it cannot.

But if we consider a quality or form in respect of its participation