Productive thinking is characterized by the sudden appearance of the solution as an insight.

真正的自由是内心的自由。

Once we dreamt that we were strangers。 We wake up to find that we were dear to each other。

The monument is a fixed point in the changing city.

行为主义者对人类行为的兴趣不仅仅是旁观者的兴趣——他想要控制人类的反应，就像物理科学家想要控制和操纵其他自然现象一样。

过去是一个萦绕现在的幽灵，无论我们是否承认。