of custom. But things "which we are accustomed to, are
pleasant," as the Philosopher says (Rhet. i, 11). Therefore movement
is not a cause of pleasure.

_On the contrary,_ Augustine says (Confess. viii, 3): "What means
this, O Lord my God, whereas Thou art everlasting joy to Thyself, and
some things around Thee evermore rejoice in Thee? What means this,
that this portion of things ebbs and flows alternately displeased and
reconciled?" From these words we gather that man rejoices and takes
pleasure in some kind of alterations: and therefore movement seems to
cause pleasure.

_I answer that,_ Three things are requisite for pleasure; two, i.e.
the one that is pleased and the pleasurable object conjoined to him;
and a third, which is knowledge of this conjunction: and in respect
of these three, movement is pleasant, as the Philosopher says (Ethic.
vii, 14 and Rhetor. i, 11). For as far as we who feel pleasure are
concerned, change is pleasant to us because our nature is changeable:
for which reason that which is suitable to us at one time is not
suitable at another; thus to warm himself at a fire is suitable to
man in winter but not in summer. Again, on the part of the pleasing
good which is united to us, change is pleasant. Because the continued
action of an agent increases its effect: thus the longer a person
remains near the fire, the more he is warmed and dried. Now the
natural mode of being consists in a certain measure; and therefore
when the continued presence of a pleasant object exceeds the measure
of one's natural mode of being, the removal of that object becomes
pleasant. On the part of the knowledge itself (change becomes
pleasant), because man desires to know something whole and perfect:
when therefore a thing cannot be apprehended all at once as a whole,
change in such a thing is pleasant, so that one part may pass and
another succeed, and thus the whole be perceived. Hence Augustine
says (Confess. iv, 11): "Thou wouldst not have the syllables stay,
but fly away, that others may come, and thou hear the whole. And so
whenever any one thing is made up of many, all of which do not exist
together, all would please collectively more than they do severally,
if all could be perceived collectively."

If therefore there be any thing, whose nature is unchangeable; the
natural mode of whose being cannot be exceeded by the continuation of
any pleasing object; and which can behold the whole object of its
delight at on