In the case of probability the contrary chances are so far related, that they determine concerning the existence or non-existence of the same object.

But this relation is far from being perfect; since some of the chances lie on the side of existence, and others on that of non-existence; which are objects altogether incompatible.

It is impossible by one steady view to survey the opposite chances, and the events dependent on them; but it is necessary, that the imagination should run alternately from the one to the other.

Each view of the imagination produces its peculiar passion, which decays away by degrees, and is followed by a sensible vibration after the stroke.

The incompatibility of the views keeps the passions from shocking in a direct line, if that expression may be allowed; and yet their relation is sufficient to mingle their fainter emotions.