Robert Louis Stevenson - In his own life, then, a man is not to...

In his own life, then, a man is not to expect happiness, only to profit by it gladly when it shall arise; he is on duty here; he knows not how or why, and does not need to know; he knows not for what hire, and must not ask. Somehow or other, though he does not know what goodness is, he must try to be good; somehow or other, though he cannot tell what will do it, he must try to give happiness to others.