Purity of heart is to will one thing.

 错误的事实对科学进步极为有害，因为它们常常长久存在。

The chief beauty about time is that you cannot waste it in advance. The next year, the next day, the next hour are lying ready for you, as perfect, as unspoiled, as if you had never wasted or misapplied a single moment in all your life. You can turn over a new leaf every hour if you choose.

一个科学家的真正价值是由他思想的独创性来衡量的。