The Gay Science Nietzsche, F. Cambridge University Press (September 17, 2001)
This book is an incredible piece of philosophic poetry. Nietzsche ruminates on loneliness better than anyone. He creates a wonderful thought experiment which asks you to imagine every part of your life eternally repeating itself. This is a sort of test to determine your attitude towards your life: if you find the thought of your life repeating again and again to be a horrible proposition, then something needs to change. However, the best part about the book is how Nietzsche presents everything. It’s so emotional and artistic. This book is the best counter to the claim that atheists are cold hearted rationalists. I feel that religion is art gone wrong in some sense and this is art done well.
It also contains the famous passage of the madman with a lit lantern in broad daylight proclaiming the death of God. Genius stuff!