The most important thing about a theory is that it explains the facts.

抽象的力量在于它允许我们忽略与当前任务无关的细节。

儿童通过自立获得身体的独立；通过自由的使用其选择能力获得意志上的独立；通过没有干扰的独立工作获得思想上的独立。

Tell the cook of this restaurant with my compliments that these are the very worst sandwiches in the whole world, and that when I ask for a watercress sandwich I do not mean a loaf with a field in the middle of it.

有些书最好的部份仅止于封面与书背。