The Complete Aristotle (eng.)

animals, trees, a painting, a
sculpture, a house, an implement); and, similarly, we think that
activities differing in kind are completed by things differing in
kind. Now the activities of thought differ from those of the
senses, and both differ among themselves, in kind; so, therefore,
do the pleasures that complete them.
    This may be seen, too, from the fact that each of the pleasures
is bound up with the activity it completes. For an activity is
intensified by its proper pleasure, since each class of things is
better judged of and brought to precision by those who engage in
the activity with pleasure; e.g. it is those who enjoy geometrical
thinking that become geometers and grasp the various propositions
better, and, similarly, those who are fond of music or of building,
and so on, make progress in their proper function by enjoying it;
so the pleasures intensify the activities, and what intensifies a
thing is proper to it, but things different in kind have properties
different in kind.
    This will be even more apparent from the fact that activities
are hindered by pleasures arising from other sources. For people
who are fond of playing the flute are incapable of attending to
arguments if they overhear some one playing the flute, since they
enjoy flute-playing more than the activity in hand; so the pleasure
connected with fluteplaying destroys the activity concerned with
argument. This happens, similarly, in all other cases, when one is
active about two things at once; the more pleasant activity drives
out the other, and if it is much more pleasant does so all the
more, so that one even ceases from the other. This is why when we
enjoy anything very much we do not throw ourselves into anything
else, and do one thing only when we are not much pleased by
another; e.g. in the theatre the people who eat sweets do so most
when the actors are poor. Now since activities are made precise and
more enduring and better by their proper pleasure, and injured by
alien pleasures, evidently the two kinds of pleasure are far apart.
For alien pleasures do pretty much what proper pains do, since
activities are destroyed by their proper pains; e.g. if a man finds
writing or doing sums unpleasant and painful, he does not write, or
does not do sums, because the activity is painful. So an activity
suffers contrary effects from its proper pleasures and pains, i.e.
from those that supervene on it in virtue of its own nature. And
alien pleasures have been stated to do much the same as pain; they
destroy the activity, only not to the same degree.
    Now since activities differ in respect of goodness and badness,
and some are worthy to be chosen, others to be avoided, and others
neutral, so, too, are the pleasures; for to each activity there is
a proper pleasure. The pleasure proper to a worthy activity is good
and that proper to an unworthy activity bad; just as the appetites
for noble objects are laudable, those for base objects culpable.
But the pleasures involved in activities are more proper to them
than the desires; for the latter are separated both in time and in
nature, while the former are close to the activities, and so hard
to distinguish from them that it admits of dispute whether the
activity is not the same as the pleasure. (Still, pleasure does not
seem to be thought or perception-that would be strange; but because
they are not found apart they appear to some people the same.) As
activities are different, then, so are the corresponding pleasures.
Now sight is superior to touch in purity, and hearing and smell to
taste; the pleasures, therefore, are similarly superior, and those
of thought superior to these, and within each of the two kinds some
are superior to others.
    Each animal is thought to have a proper pleasure, as it has a
proper function; viz. that which corresponds to its activity. If we
survey them species by species, too, this will be evident; horse,
dog, and man have different pleasures, as Heraclitus says ‘asses
would prefer sweepings to gold’; for food is pleasanter than gold
to asses. So the pleasures of creatures different in kind differ in
kind, and it is plausible to suppose that those of a single species
do not differ. But they vary to no small extent, in the case of men
at least; the same things delight some people and pain others, and
are painful and odious to some, and pleasant to and liked by
others. This happens, too, in the case of sweet things; the same
things do not seem sweet to a man in a fever and