The question of what happiness actually is has puzzled humankind since time immemorial. After all, it was one of the first issues that the early Greek philosophers turned to. They called it eudaimonia, a term that encompasses prosperity and good fortune as well as happiness.
The question troubled Arthur Schopenhauer, too, and in his 1851 philosophical essay "The Wisdom of Life" he presents his own thoughts on the matter. He attempts both to define what happiness is and to ascertain how life should be lived so as to achieve it, how one should order his life so as to obtain the greatest possible amount of pleasure and success. According to him, that is the only way to gain the wisdom of life.