"Randomized experiments are the gold standard for causal inference, but they are not always feasible."

在现实生活中，善与恶的战争中最困难的一面是决定谁是善谁是恶。

"In the fields of observation chance favors only the prepared mind."

To forget is to betray; to remember is to resist.

The doorway to happiness opens from the inside.

故事是承载思想的工具，而不是相反。