everything that will affect either it or ourselves with sorrow.

This reciprocity of hatred may also arise from the fact that hatred is
followed by an attempt to bring evil upon him who is hated. If,
therefore, we imagine that we are hated by any one else, we shall
imagine him as the cause of some evil or sorrow, and thus we shall be
affected with sorrow or apprehension accompanied with the idea of the
person who hates us as a cause; that is to say, we shall hate him in
return, as we have said above.

If we imagine that the person we love is affected with hatred towards
us, we shall be agitated at the same time both with love and hatred. For
in so far as we imagine that we are hated are we determined to hate him
in return. But (by hypothesis) we love him notwithstanding, and
therefore we shall be agitated both by love and hatred.

If we imagine that an evil has been brought upon us through the hatred
of some person towards whom we have hitherto been moved by no emotion,
we shall immediately endeavor to return that evil upon him.

If we imagine that any one like ourselves is affected with hatred
towards an object like ourselves which we love, we shall hate him. If we
imagine that we are beloved by a person without having given any cause
for the love we shall love him in return.

If we imagine that we have given just cause for love, we shall pride
ourselves upon it. This frequently occurs, and we have said that the
contrary takes place when we believe that we are hated by another
person. This reciprocal love, and consequently this attempt to do good
to the person who loves us, and who endeavors to do good to us, is
called _thankfulness_ or _gratitude_, and from this we can see how much
readier men are to revenge themselves than to return a benefit.

If we imagine that we are loved by a person we hate, we shall at the
same time be agitated both by love and hatred. If the hatred prevail, we
shall endeavor to bring evil upon the person by whom we are loved. This
emotion is called Cruelty, especially if it is believed that the person
who loves has not given any ordinary reason for hatred.

_The "Herd Instinct"_

If we imagine men to love or hate a thing, we shall therefore love or
hate it; that is to say, we shall therefore rejoice or be sad at the
presence of the thing, and therefore we shall endeavor to do everything
which we imagine men[28] will look upon with joy, and, on the contrary,
we shall be averse to doin