ss Is a Cause of Love?

Objection 1: It would seem that likeness is not a cause of love. For
the same thing is not the cause of contraries. But likeness is the
cause of hatred; for it is written (Prov. 13:10) that "among the
proud there are always contentions"; and the Philosopher says (Ethic.
viii, 1) that "potters quarrel with one another." Therefore likeness
is not a cause of love.

Obj. 2: Further, Augustine says (Confess. iv, 14) that "a man loves
in another that which he would not be himself: thus he loves an
actor, but would not himself be an actor." But it would not be so, if
likeness were the proper cause of love; for in that case a man would
love in another, that which he possesses himself, or would like to
possess. Therefore likeness is not a cause of love.

Obj. 3: Further, everyone loves that which he needs, even if he have
it not: thus a sick man loves health, and a poor man loves riches.
But in so far as he needs them and lacks them, he is unlike them.
Therefore not only likeness but also unlikeness is a cause of love.

Obj. 4: Further, the Philosopher says (Rhet. ii, 4) that "we love
those who bestow money and health on us; and also those who retain
their friendship for the dead." But all are not such. Therefore
likeness is not a cause of love.

_On the contrary,_ It is written (Ecclus. 13:19): "Every beast loveth
its like."

_I answer that,_ Likeness, properly speaking, is a cause of love. But
it must be observed that likeness between things is twofold. One kind
of likeness arises from each thing having the same quality actually:
for example, two things possessing the quality of whiteness are said
to be alike. Another kind of likeness arises from one thing having
potentially and by way of inclination, a quality which the other has
actually: thus we may say that a heavy body existing outside its
proper place is like another heavy body that exists in its proper
place: or again, according as potentiality bears a resemblance to its
act; since act is contained, in a manner, in the potentiality itself.

Accordingly the first kind of likeness causes love of friendship or
well-being. For the very fact that two men are alike, having, as it
were, one form, makes them to be, in a manner, one in that form: thus
two men are one thing in the species of humanity, and two white men
are one thing in whiteness. Hence the affections of one tend to the
other, as being one with him; and he wishes good to him as to