A thirsty optimist saw a cup filled to midway with wine and rejoices that it is half full, whereas the pessimist, perceiving the same vessel, laments that it is half empty.

But is not the so-called optimist, who is truly the pessimist? For had he not expected the cup to be completely empty, he would not rejoice at its being half full. The so-called pessimist, on the other hand, is disappointed, since his expectation was for a measure of overbrimming - thus he is in truth the optimist.