There is only one corner of the universe you can be certain of improving, and that's your own self. Aldous Huxley
Most people would rather be certain they're miserable, than risk being happy. Robert Anthony
Ultimately a hero is a man who would argue with the gods, and so awakens devils to contest his vision. The more a man can achieve, the more he may be certain that the devil will inhabit a part of his creation. Norman Mailer
To be uncertain is to be uncomfortable, but to be certain is to be ridiculous. Chinese Proverb
If the rich man is fawning over the poor man, you can be certain that he needs something. Sicilian Proverb
Be certain and on the level. American Proverb