This may be the best one of all the Feynman videos. He explains how physicists do mathematics and distinguishes how physicists do math from how mathematicians do math. He describes the two flavors as Greek and Babylonian.

The money quote if you don't have time to watch it: "Physicists do Babylonian mathematics and pay little attention to precise reasoning from fixed axioms."

Comment number 1; the quality of the video ain't all that great--in particular there is an annoying very small synch error which is just large enough to be definitely noticeable. Nevertheless it is absorbing because of the power of his presentation. The occasional audience shots show an audience *transfixed.* They also show the majority of the people wearing eyeglasses.

Comment number 2; in his earlier days his working class New York accent seemed far more obvious. I am reminded of Art Carney from The Honeymooners. (That is a four minute clip.) Feynman was born in Queens in 1918. Carney was born in Mount Vernon in 1918.

Here is another snip from the text. It is from lecture # 3 The great conservation principles.

"For those who want some proof that physicists are human, the proof is in the idiocy of all the different units they use for measuring energy." (p 75 of the 1967 MIT press edition)