Paul Ehrenfest quotes:

Physics is simple, but subtle.

A thesis has to be presentable... but don't attach too much importance to it. If you do succeed in the sciences, you will do later on better things and then it will be of little moment. If you don't succeed in the sciences, it doesn't matter at all.

Don't be impatient with me. Bear in mind that I hop around among all of you big beasts like a harmless and helpless frog who is afraid of being squashed.

No two electrons in the same state? That is why atoms are so unnecessarily big, and why metal and stone are so bulky.

You will get your difficulties with the point electron.