Ohm (a distinguished mathematician, be it noted) brought into order a host of puzzling facts connecting electromotive force and electric current in conductors, which all previous electricians had only succeeded in loosely binding together qualitatively under some rather vague statements. Even as late as 20 years ago, "quantity" and "tension" were much used by men who did not fully appreciate Ohm's law.

Euclid for children is barbarous.

Criticized for using formal mathematical manipulations, without understanding how they worked: Should I refuse a good dinner simply because I do not understand the process of digestion?

The best result of mathematics is to be able to do without it.

Waves from moving sources: Adagio. Andante. Allegro moderato.

...there is no absolute scale of size in nature, and the small may be as important, or more so than the great.

Logic can be patient, for it is eternal.