The concept of NP-completeness has provided a powerful tool for understanding the complexity of computational problems.

The magi, as you know, were wise men—wonderfully wise men—who brought gifts to the Babe in the manger. They invented the art of giving Christmas presents. Being wise, their gifts were no doubt wise ones, possibly bearing the privilege of exchange in case of duplication.

一个人的行为不是由他的种族归属决定的，而是由他的祖先特征和文化环境决定的。

自然的简单性不应以我们对简单性的概念来衡量。