You can convince an ignorant man easily you can convince a wise man more easily. But a man who knows a little and thinks himself to be perfect, not even Brahma can convince. (Indian Proverb) - More Indian Proverbs...
Correct a wise man, and he will be grateful; correct a fool, and he will not only give a deaf ear, but send you off with a flea in your ear. (Latin Proverb) - More Latin Proverbs...