ough perhaps it may be oftener turned
to the one side than the other, it is impossible for it, by reason of
the opposition of causes or chances, to rest on either. The pro and con
of the question alternately prevail; and the mind, surveying the object
in its opposite principles, finds such a contrariety as utterly destroys
all certainty and established opinion.

Suppose, then, that the object, concerning whose reality we are
doubtful, is an object either of desire or aversion, it is evident,
that, according as the mind turns itself either to the one side or the
other, it must feel a momentary impression of joy or sorrow. An object,
whose existence we desire, gives satisfaction, when we reflect on those
causes, which produce it; and for the same reason excites grief
or uneasiness from the opposite consideration: So that as the
understanding, in all probable questions, is divided betwixt the
contrary points of view, the affections must in the same manner be
divided betwixt opposite emotions.

Now if we consider the human mind, we shall find, that with regard to
the passions, it is not the nature of a wind-instrument of music, which
in running over all the notes immediately loses the sound after the
breath ceases; but rather resembles a string-instrument, where after
each stroke the vibrations still retain some sound, which gradually and
insensibly decays. The imagination is extreme quick and agile; but the
passions are slow and restive: For which reason, when any object is
presented, that affords a variety of views to the one, and emotions to
the other; though the fancy may change its views with great celerity;
each stroke will not produce a clear and distinct note of passion,
but the one passion will always be mixt and confounded with the other.
According as the probability inclines to good or evil, the passion of
joy or sorrow predominates in the composition: Because the nature of
probability is to cast a superior number of views or chances on one
side; or, which is the same thing, a superior number of returns of
one passion; or since the dispersed passions are collected into one, a
superior degree of that passion. That is, in other words, the grief and
joy being intermingled with each other, by means of the contrary views
of the imagination, produce by their union the passions of hope and
fear.

Upon this head there may be started a very curious question concerning
that contrariety of passions, which is our present