On the Heights of Despair
Emil M. Cioran
On the Heights of Despair shows Cioran's first grappling with themes he would return to in his mature works: despair and decay, absurdity and alienation, futility and the irrationality of existence. It also presents Cioran as a connoisseur of apocalypse, a theoretician of despair, for whom writing and philosophy both share the "lyrical virtues" that alone lead to a metaphysical revelation.
"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them. The full list is here.