Hallucinations, including hearing voices, are a common symptom of schizophrenia. Some scholars say van Gogh’s behaviors may have stemmed from that disorder. According to one account, van Gogh, during an argument with fellow painter Paul Gauguin, heard someone in his ear say, "Kill him." Instead, van Gogh took a knife and cut off part of his own ear. Some psychiatrists think he might have had depression or bipolar disorder instead.