cause it is the cause of
pleasure. Therefore pleasure does not hinder the use of reason.

_On the contrary,_ The Philosopher says (Ethic. vi, 5), that
"pleasure destroys the estimate of prudence."

_I answer that,_ As is stated in _Ethic._ x, 5, "appropriate
pleasures increase activity . . . whereas pleasures arising from
other sources are impediments to activity." Accordingly there is a
certain pleasure that is taken in the very act of reason, as when one
takes pleasure in contemplating or in reasoning: and such pleasure
does not hinder the act of reason, but helps it; because we are more
attentive in doing that which gives us pleasure, and attention
fosters activity.

On the other hand bodily pleasures hinder the use of reason in three
ways. First, by distracting the reason. Because, as we have just
observed, we attend much to that which pleases us. Now when the
attention is firmly fixed on one thing, it is either weakened in
respect of other things, or it is entirely withdrawn from them; and
thus if the bodily pleasure be great, either it entirely hinders the
use of reason, by concentrating the mind's attention on itself; or
else it hinders it considerably. Secondly, by being contrary to
reason. Because some pleasures, especially those that are in excess,
are contrary to the order of reason: and in this sense the
Philosopher says that "bodily pleasures destroy the estimate of
prudence, but not the speculative estimate," to which they are not
opposed, "for instance that the three angles of a triangle are
together equal to two right angles." In the first sense, however,
they hinder both estimates. Thirdly, by fettering the reason: in so
far as bodily pleasure is followed by a certain alteration in the
body, greater even than in the other passions, in proportion as the
appetite is more vehemently affected towards a present than towards
an absent thing. Now such bodily disturbances hinder the use of
reason; as may be seen in the case of drunkards, in whom the use of
reason is fettered or hindered.

Reply Obj. 1: Bodily pleasure implies indeed repose of the appetite
in the object of pleasure; which repose is sometimes contrary to
reason; but on the part of the body it always implies alteration.
And in respect of both points, it hinders the use of reason.

Reply Obj. 2: The powers of the appetite and of apprehension are
indeed distinct parts, but belonging to the one soul. Consequently
when the soul is very intent o