Only a life lived for others is a life worthwhile.
只有为他人的幸福而活得生活才是有意义的生活

Only one who devotes himself to a cause with his whole strength and soul can be a true master. For this reason mastery demands all of a person.
只有当一个人把他全部的精力都投入到一件事当中的时候，他才有可能成为一个真正的大师。因为一个人要付出他的全部才能达到真正的精通

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
只有两件事是无穷的-- 宇宙的浩渺和人类的愚蠢-- 而且对前者我并不十分确定

People love chopping wood. In this activity one immediately sees results.
人们爱砍柴，因为这是一项马上就可以看到结果的活动

继续

The difference between genius and stupidity is that genius has its limits.
聪慧和愚蠢之间的差别就是聪慧是有界限的

The faster you go, the shorter you are.
你的速度越快，你的尺寸就越短（相对论原来可以解释得这么简单）

The grand aim of all science is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms.
科学宏大的目标就是把最多的事实浓缩进最少的假说和公理之中

The only reason for time is so that everything doesn't happen at once.
时间的存在是为了不要让所有的事件同时发生

The pursuit of truth and beauty is a sphere of activity in which we are permitted to remain children all our lives.
在追求真理和美的领域里，我们可以一辈子做一个孩子

The value of a man should be seen in what he gives and not in what he is able to receive.
对一个人的价值的评估是要看他给予了这个社会什么，而不是他能从这个社会索取什么

We cannot despair of humanity, since we ourselves are human beings.
我们不能对人性绝望，因为我们自己也是人

You cannot simultaneously prevent and prepare for war.
你不能在阻止战争的同时准备战争（笑，多讽刺）

If you want your children to be intelligent, read them fairy tales. If you want them to be more intelligent, read them more fairy tales.
如果想要你的孩子变成一个聪明的孩子，给他读些童话吧。如果想要你的孩子再变聪明一点，再给他多读一些童话吧