[seanstickle]

This is how I learned proofs:

http://i.imgur.com/omXqvos.png

Well, technically I learned proofs from Euclid first. But this book followed close behind.

Clear and comprehensible (once you learn the basic symbols). Very much structured. There's hardly any prose in the whole two volumes.

[Enzolangellotti]

Care to share the title?

[seanstickle]

Principia Mathematica

http://en.wikipedia.org/wiki/Principia_Mathematica