6. It is a probable good or evil, which commonly causes hope or fear; because probability, producing an inconstant and wavering survey of an object, occasions naturally a like mixture and uncertainty of passion. But we may observe, that, wherever, from other causes, this mixture can be produced, the passions of fear and hope will arise, even tho' there be no probability.
An evil, conceived as barely possible, sometimes produces fear; especially if the evil be very great. A man cannot think of excessive pain and torture without trembling, if he runs the least risque of suffering them. The smallness of the probability is compensated by the greatness of the evil.
But even impossible evils cause fear; as when we tremble on the brink of a precipice, tho' we know ourselves to be in perfect security, and have it in our choice, whether we will advance a step farther. The immediate presence of the evil influences the imagination and produces a species of belief; but being opposed by the reflection on our security, that belief is im-mediately
