m disease."

_I answer that,_ We speak of that as being natural, which is in
accord with nature, as stated in _Phys._ ii, 1. Now, in man, nature
can be taken in two ways. First, inasmuch as intellect and reason is
the principal part of man's nature, since in respect thereof he has
his own specific nature. And in this sense, those pleasures may be
called natural to man, which are derived from things pertaining to
man in respect of his reason: for instance, it is natural to man to
take pleasure in contemplating the truth and in doing works of
virtue. Secondly, nature in man may be taken as contrasted with
reason, and as denoting that which is common to man and other
animals, especially that part of man which does not obey reason. And
in this sense, that which pertains to the preservation of the body,
either as regards the individual, as food, drink, sleep, and the
like, or as regards the species, as sexual intercourse, are said to
afford man natural pleasure. Under each kind of pleasures, we find
some that are _not natural_ speaking absolutely, and yet _connatural_
in some respect. For it happens in an individual that some one of the
natural principles of the species is corrupted, so that something
which is contrary to the specific nature, becomes accidentally
natural to this individual: thus it is natural to this hot water to
give heat. Consequently it happens that something which is not
natural to man, either in regard to reason, or in regard to the
preservation of the body, becomes connatural to this individual man,
on account of there being some corruption of nature in him. And this
corruption may be either on the part of the body--from some ailment;
thus to a man suffering from fever, sweet things seem bitter, and
vice versa--or from an evil temperament; thus some take pleasure in
eating earth and coals and the like; or on the part of the soul; thus
from custom some take pleasure in cannibalism or in the unnatural
intercourse of man and beast, or other such things, which are not in
accord with human nature.

This suffices for the answers to the objections.
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EIGHTH ARTICLE [I-II, Q. 31, Art. 8]

Whether One Pleasure Can Be Contrary to Another?

Objection 1: It would seem that one pleasure cannot be contrary to
another. Because the passions of the soul derive their species and
contrariety from their objects. Now the object of pleasure is the
good. Since therefore good is not contrary to