Paul Halmos on Prerequisites

Definitely the quote of the day:

…[the reader] should not be discouraged, if on first reading of section 0, he finds that he does not have the prerequisites for reading the prerequisites.

Paul Halmos (1916 – 2006, Hungarian-born American mathematician
in Measure Theory (1950)

This is essentially the mathematician’s equivalent of the adage “Fake it ’til you make it.”