变体：有七个原因决定了所有人类的行动：机遇、本性、强迫、习惯、理性、激情和欲望。
Variant: All human actions have one or more of these seven causes: chance, nature, compulsions, habit, reason, passion and desire.
数学的本质在于它的自由。
你想要的每一样东西都在恐惧的另一边。
我喜欢挑战自己。
"The only limit to our realization of tomorrow is our doubts of today."