每一种化合物都必须有确定的组成，这可以用其元素的符号来表示。

To find out what one is fitted to do, and to secure an opportunity to do it, is the key to happiness.

"You have to believe in the long term plan you have but you need the short term goals to motivate and inspire you."

每种心理状态都是大脑某种物理状态的功能。