If I had felt then as I feel now, or as I felt a few years after I had married her, nothing could possibly have persuaded me to marry a woman who smoked. Dates, yes. Sexual adventures, yes. But to pin myself permanently inside closed quarters with a smoker? Never. Never. Never. Beauty wouldn't count, sweetness wouldn't count, suitability in every other respect wouldn't count.

I write for the same reason I breathe - because if I didn't, I would die.

During the century after Newton, it was still possible for a man of unusual attainments to master all fields of scientific knowledge. But by 1800, this had become entirely impracticable.

Pierre Curie, a brilliant scientist, happened to marry a still more brilliant one-Marie, the famous Madame Curie-and is the only great scientist in history who is consistently identified as the husband of someone else.

Science can be introduced to children well or poorly. If poorly, children can be turned away from science; they can develop a lifelong antipathy; they will be in a far worse condition than if they had never been introduced to science at all.

He had read much, if one considers his long life; but his contemplation was much more than his reading. He was wont to say that if he had read as much as other men he should have known no more than other men.

After years of finding mathematics easy, I finally reached integral calculus and came up against a barrier. I realized that this was as far as I could go, and to this day I have never successfully gone beyond it in any but the most superficial way.