The world we live in is a world of mingled good and evil. Whether it is chiefly good or chiefly bad depends on how we take it. To look at the world in such a way as to emphasize the evil is the art of pessimism. To look at it in such a way as to bring out the good, and throw the evil into the background, is the art of optimism. The facts are the same in either case. It is simply a question of perspective and emphasis.

The Art of Optimism as Taught by Robert Browning (ed. 1900)