A masterpiece by Stendhal. It's been on my bookshelf for 4 years but I somehow never felt compelled to read it... until now. It explores in depth some of the most beautiful aspects of human nature (love, trust), but as a result also reveals the downsides: mimetic desires (jealousy), vanity, rivalry, and hypocrisy.
What is fascinating is that each character is carefully analyzed from a psychological standpoint. The protagonist leaves nobody indifferent. Definitely a lot to learn from his story.