在观察性研究中，我们常常不得不依赖于无法直接检验的假设。
"In observational studies, we often have to rely on assumptions that are not directly testable."
The past is a foreign country; they do things differently there.
普通和非凡的区别在于那一点点额外的努力。
Overtaking on curves requires knowing where the curves are.
The first question I ask myself when something doesn't seem to be beautiful is why do I think it's not beautiful. And very shortly you discover that there is no reason.
The land teaches patience; the market teaches agility.
