Letters 98.1

You need never believe that anyone who depends upon happiness is happy! It is a fragile support—this delight in adventitious things; the joy which entered from without will some day depart. But that joy which springs wholly from oneself is leal and sound; it increases and attends us to the last; while all other things which provoke the admiration of the crowd are but temporary Goods. You may reply: “What do you mean? Cannot such things serve both for utility and for delight?” Of course. But only if they depend on us, and not we on them.

Seneca, Letters to Lucilius 98.1, translated by Richard Mott Gummere