Arthur Schopenhauer

Schopenhauer took Kant's thing-in-itself and gave it a name: Will. Behind the phenomenal world of objects and laws, the inner reality of everything that exists is a blind, restless, purposeless striving. You feel it directly in your own body — as hunger, as desire, as the will to live. The rest of reality is the same Will, seen from outside.

The consequence is bleak: life is suffering, because the Will always wants more than it has, and satisfaction merely sets the next desire in motion. Schopenhauer was Europe's first philosopher to take Buddhism seriously, and his answer to suffering is recognizably Buddhist — quiet the Will, through aesthetic contemplation, compassion, or ascetic renunciation.

He spent decades furious that no one read him while Hegel filled lecture halls. Late in life he became famous, and Nietzsche, Wagner, Tolstoy, Wittgenstein, and Freud all read him with awe.