The March trilogy, John Lewis's memoir about the Civil Rights movement, is essential as both a historical work and an introduction to the art of resistance.
If you want the nitty-gritty about Canadian politics, the stories told by former MPs in "Tragedy in the Commons" are a gold mine of information.
It may not have been intended for publication, but Meditations by Marcus Aurelius has become a touchstone since it was first written nearly 2000 years ago.
Facism: A Very Short Introduction is indeed very short, but it's brevity didn't do me any favours. A lot of my questions about politics remain unanswered.