Thus the prospect of past pain is agreeable, when we are satisfyed with our present condition; as on the other hand our past pleasures give us uneasiness, when we enjoy nothing at present equal to them.

The comparison being the same, as when we reflect on the sentiments of others, must be attended with the same effects.
Nay a person may extend this malice against himself, even to his present fortune, and carry it so far as designedly to seek affliction, and encrease his pains and sorrows.

This may happen upon two occasions.
First, Upon the distress and misfortune of a friend, or person dear to him.

Secondly, Upon the feeling any remorses for a crime, of which he has been guilty.

It is from the principle of comparison that both these irregular appetites for evil arise.