Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful.

一个社会的真正考验在于它如何对待最脆弱的成员。

解析：强调实践的重要性。

"The lifeblood of any business is its customers."

量子理论的发展表明，经典的空间和时间概念不足以在最基本的层面上描述物理世界。