Richard P. Feynman

"This is the third of four lectures on a rather difficult subject -- the
theory of quantum electrodynamics -- and since there are obviously more
people here tonight than there were before, some of you haven't heard the
other two lectures and will find this lecture almost incomprehensible.
Those of you who *have* heard the other two lectures will also find this
lecture incomprehensible, but you know that that's all right: as I
explained in the first lecture, the way we have to describe Nature is
generally incomprehensible to us."

One does not, by knowing all the physical laws as we know them
today, immediately obtain an understanding of anything much.

I love only nature, and I hate mathematicians.

Physics is to Math what Sex is to Masturbation

Physics is like sex: sure, it may give some practical results, but that's
not why we do it.

What I am going to tell you about is what we teach our physics students in
the third or fourth year of graduate school... It is my task to convince
you not to turn away because you don't understand it. You see my physics
students don't understand it... That is because I don't understand it.
Nobody does.

For those who want some proof that physicists are human, the
proof is in the idiocy of all the different units which they use for
measuring energy.