The artist described above spent most of his life in poverty and haunted by mental illness.
In addition to the hospitalizations mentioned in the Starry, Starry Night node, he was often banished from the places he was working due to his strange behavior

Like many great artists, he was truly out of touch with those around him, for reasons related to both:
1. the kind of paintings he was creating (odd, slightly blurry images of the world, filled with swirling action and vibrant color, compare his use of a color to the dark, muted tones of Rembrandt, the more famous Dutch artist).
2. His real mental illness (likely paranoid schizophrenia due to his reclusive nature, interrupted by serious conflicts with peers, but who's to say, really).

His most celebrated "crazy" act was cutting off his own ear and sending it to a woman he knew. There are a number of theories about this, but the one most widely held is that he had been reading about bullfighters who brought the ears of vanquished cattle to their loves.
In Vincent's mind this was a way to show this woman she had slayed him, literally and figuratively.

Vincent is the poster child for the tortured genius.