Dictators fall when they're overconfident; they stay in power when they're paranoid.

Never be afraid to fail. Failure is only a stepping stone to improvement. Never be overconfident because that will block your improvement.

Life is not a bed of roses. When things move in the way one wishes, one becomes overconfident that fate will always be with us. Rarely do we realize that it is only like a dormant volcano, ready to erupt any time. The volcano which would totally devastate was also waiting to make its nasty appearance. It did send its tremors, but we could not decipher it in time. The result was that we spread out like molten lava in various directions.

Every time I begin to feel overconfident about a theory or an idea of mine, an underlying, somewhat uneasy feeling invariably visits me.