"When I was a boy there were two curious men running about who were called the optimist and the pessimist. I constantly used the words myself, but I cheerfully confess that I never had any very special idea of what they meant. The only thing which might be considered evident was that they could not mean what they said; for the ordinary verbal explanation was that the optimist thought this world as good as it could be, while the pessimist thought it as bad as it could be. Both these statements being obviously raving nonsense, one had to cast about for other explanations. An optimist could not mean a man who thought everything right and nothing wrong. For that is meaningless; it is like calling everything right and nothing left. Upon the whole, I came to the conclusion that the optimist thought everything good except the pessimist, and that the pessimist thought everything bad, except himself."