ther, one contrary is not the matter of the other; because
contraries cannot co-exist together. But sorrow can be the matter of
pleasure; for Augustine says (De Poenit. xiii): "The penitent should
ever sorrow, and rejoice in his sorrow." The Philosopher too says
(Ethic. ix, 4) that, on the other hand, "the evil man feels pain at
having been pleased." Therefore pleasure and pain are not contrary to
one another.

_On the contrary,_ Augustine says (De Civ. Dei xiv, 6) that "joy is
the volition of consent to the things we wish: and that sorrow is the
volition of dissent from the things we do not wish." But consent and
dissent are contraries. Therefore pleasure and sorrow are contrary to
one another.

_I answer that,_ As the Philosopher says (Metaph. x, 4), contrariety
is a difference in respect of a form. Now the form or species of a
passion or movement is taken from the object or term. Consequently,
since the objects of pleasure and sorrow or pain, viz. present good
and present evil, are contrary to one another, it follows that pain
and pleasure are contrary to one another.

Reply Obj. 1: Nothing hinders one contrary causing the other
accidentally: and thus sorrow can be the cause of pleasure. In one
way, in so far as from sorrow at the absence of something, or at the
presence of its contrary, one seeks the more eagerly for something
pleasant: thus a thirsty man seeks more eagerly the pleasure of a
drink, as a remedy for the pain he suffers. In another way, in so far
as, from a strong desire for a certain pleasure, one does not shrink
from undergoing pain, so as to obtain that pleasure. In each of these
ways, the sorrows of the present life lead us to the comfort of the
future life. Because by the mere fact that man mourns for his sins,
or for the delay of glory, he merits the consolation of eternity. In
like manner a man merits it when he shrinks not from hardships and
straits in order to obtain it.

Reply Obj. 2: Pain itself can be pleasurable accidentally in so far
as it is accompanied by wonder, as in stage-plays; or in so far as it
recalls a beloved object to one's memory, and makes one feel one's
love for the thing, whose absence gives us pain. Consequently, since
love is pleasant, both pain and whatever else results from love,
forasmuch as they remind us of our love, are pleasant. And, for this
reason, we derive pleasure even from pains depicted on the stage: in
so far as, in witnessing them, we perceive oursel