The Meaning of Optimism and Pessimism
"Is the glass half empty or half full?" has become the classic test to determine whether someone is an optimist or a pessimist. It doesn't work. All it actually tells you is whether the questioned is bright enough to reply "Both" or pedantic enough to ask "What glass?".
The problem is that pessimism and optimism are not descriptions of a person's power of perception, but of their expectations. A man who saw a glass and thought it not half full but half empty, would not be a pessimist, he would be delusional. The man who expected that should he try the beverage, it would make him sick, might well be a pessimist.
The pessimist is not perpetually sad, any more than the optimist is perpetually happy. Instead the pessimist keeps expecting that he will soon be very sad, and being pleasantly surprised, and the optimist that he will soon be very happy; he is always being disappointed.
The man who in no circumstance will believe that any good is presently happening to him is not a pessimist, he is a cynic. The man who is only a pessimist acknowledges good when it happens, and, if he has any sense, resolves to enjoy it while it lasts, but not grow used to it, for he expects it to end shortly.
Some while ago I encountered a quote on this subject which I rather enjoyed, it read "The optimist declares that we live in the best of all words, the pessimist fears this may be true" while witty it is rather inaccurate. The man who presumes to comment on the existence of other worlds, let alone their characteristics, is not an optimist, but a fool. It is however true that the pessimist expects never to find anywhere more pleasant than the place he presently occupies (it is the cynic who fears he lives the worst of all lives).
Pessimism then is not an evil, nor is optimism a virtue, the evil is the delusion of cynicism, the virtue the strength of resisting it. The true pessimist enjoys today, prepares for tomorrow, and awakes each morning in delight that the universe has again blessed him beyond all his expectations.