Optimism (n.) is a great help in achieving success, or getting along without it.
Optimism (n.) is a state of mind that believes matrimony will be cheaper than the courtship.
Optimism (n.) is complemented well in a partnership by a pessimist because one sees the profits while the other sees the risks.
Optimism (n.) is feeling kindly toward everyone because one hasn't been cheated yet.
Optimism (n.) is having the right feelings for the wrong reasons.
Optimism (n.) is looking at an oyster and expecting a pearl while pessimism is looking at an oyster and expecting ptomaine poisoning.
Optimism (n.) is one who sees a light where there is none while a pessimist is one who tries to put it out.
Optimism (n.) is the belief that even when worst comes to worst, it won't be so bad.
Optimism (n.) is thinking the realist is a pessimist while pessimism is thinking the realist is an optimist.