凡是能够说的事情，都能够说清楚；而对于不能谈论的事情，就必须保持沉默。
What can be said at all can be said clearly; and whereof one cannot speak thereof one must be silent.
Health is not a privilege of the rich, but a vulnerability of the poor.
数学家研究纯数学不是因为它有用；他研究它是因为他喜欢它，他喜欢它是因为它美丽。