"Causal inference requires careful thought about the assumptions underlying your analysis."

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.

宇宙即变化；我们的生活由我们的思想塑造。

Happiness is not something ready made. It comes from your own actions.