It's better to work with a nice category containing some nasty objects, than a nasty category containing only nice objects.

- John C. Baez

Any effect, constant, theorem or equation named after Professor X was first discovered by Professor Y , for some value of Y not equal to X.

- John C. Baez

Why speculate when you can calculate?

- John C. Baez

... commutative algebra is a lot like topology, only backwards.

- John C. Baez

When somebody says to me-which they do like every 5 years- "How does it feel to be over the hill?" my response is, "I'm just heading up the mountain."

- John C. Baez