BOOK II PART II
same manner as I love a brother or country-
man. A rival has almost as close a relation to
me as a partner. For as the pleasure of the latter
causes my pleasure, and his pain my pain; so
the pleasure of the former causes my pain, and
his pain my pleasure. The connexion, then, of
cause and effect is the same in both cases; and
if in the one case, the cause and effect have a
farther relation of resemblance, they have that
of contrariety in the other; which, being also a
species of resemblance, leaves the matter pretty
equal.
The only explication, then, we can give of
this phaenomenon is derived from that prin-
ciple of a parallel direction above-mentioned.
Our concern for our own interest gives us a
pleasure in the pleasure, and a pain in the
pain of a partner, after the same manner as by