More quotations especially for teachers:
There is no Royal Road to Geometry.
— Euclid
Teaching is the royal road to learning.
The title which I most covet is that of teacher. The writing of a research paper and the teaching of freshman calculus, and everything in between, falls under this rubric. Happy is the person who comes to understand something and then gets to explain it.
Denise Gaskins' Let's Play Math 