Pleasure is pure, pain is always tempered

When we suffer, we gain the pleasure of hoping for the end of our suffering; and we are never wrong, for we have at least the resource of sleep, in which good dreams console and soothe us; and when we are happy, the thought that our happiness will be followed by misery never comes to trouble us. Pleasure, then, when it is present, is always pure; pain is always tempered.

Giacomo Casanova - History of my life (2, 1)