唯一安全的系统是关闭的，浇筑在混凝土块中，并密封在有武装警卫的铅衬房间中。

If you don’t make mistakes, you’re not working on hard enough problems.

The only thing that can bring you happiness is yourself.

Every improvement in the circumstances of the society tends either directly or indirectly to raise the real rent of land, to increase the real wealth of the landlord, his power of purchasing the labour, or the produce of the labour of other people.

The greatest danger to American agriculture is the loss of the family farm.

Curiosity and persistence are the driving forces behind scientific breakthroughs.

快乐是生活的关键。没有快乐，你就一无所有。