Joy sparks the urge to play, interest sparks the urge to explore, contentment sparks the urge to savor and integrate, and love sparks a recurring cycle of each of these urges within safe, close relationships.

经济学的第一课是稀缺：从来没有足够的任何一种东西能够满足所有人对其需要。政治学的第一课是摒弃经济学的第一课。

数学的美在于它既精确又富有创造性。