external body. Therefore, if
we imagine any one who is like ourselves to be affected by a
modification, this imagination will express a modification of our body
like that modification, and therefore we shall be modified with a
similar modification ourselves, because we imagine something like us to
be modified with the same. If, on the other hand, we hate a thing which
is like ourselves, we shall so far be modified by a modification
contrary and not similar to that with which it is modified.

If we imagine that a person enjoys a thing, that will be a sufficient
reason for making us love the thing and desiring to enjoy it. If we
imagine that a person enjoys a thing which only one can possess, we do
all we can to prevent his possessing it. His enjoyment of the thing is
an obstacle to our joy, and we endeavor to bring into existence
everything which we imagine conduces to joy, and to remove or destroy
everything opposed to it, or which we imagine conduces to sorrow.

We see, therefore, that the nature of man is generally constituted so as
to pity those who are in adversity and envy those who are in prosperity,
and he envies with a hatred which is the greater in proportion as he
loves what he imagines another possesses. We see also that from the same
property of human nature from which it follows that men pity one another
it also follows that they are envious and ambitious. If we will consult
experience, we shall find that she teaches the same doctrine, especially
if we consider the first years of our life. For we find that children,
because their body is, as it were, continually in equilibrium, laugh and
cry merely because they see others do the same; whatever else they see
others do they immediately wish to imitate; everything which they think
is pleasing to other people they want. And the reason is, as we have
said, that the images of things are the modifications themselves of the
human body, or the ways in which it is modified by external causes and
disposed to this or that action.

II

If we imagine that we are hated by another without having given him any
cause for it, we shall hate him in return. If we imagine that we have
given just cause for the hatred, we shall then be affected with shame.
This, however, rarely happens; we endeavor to affirm everything, both
concerning ourselves and concerning the beloved object which we imagine
will affect us or the object with joy, and, on the contrary, we endeavor
to deny