When nothing is sure, everything is possible. We must leave our mark on life while we have it in our power, lest it should close up, when we leave it, without a trace. The minute you settle for less than you deserve, you get even less than you settled for.
Energy creates energy.
It is by spending oneself that one becomes rich. You've got to take the initiative and play your game. In a decisive set, confidence is the difference. No other field can offer, to such an extent as mathematics, the joy of discovery, which is perhaps the greatest human joy. I think the one lesson I have learned is that there is no substitute for paying attention.