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)

Pharaoh Amasis knew how to divide time between duty and pleasure

' Archers, Amasis replied, string their bows when they wish to shoot, and unstring them after use. A bow kept always strung would break, and so be useless when it was needed. It is the same with a man; anyone who was always serious, and never allowed himself a fair share of relaxation and amusement, would suddenly go off his head, or get a stroke. It is because I know this that I divide my time between duty and pleasure. '

Herodotus - Histories (II, 173)