Late in the evening of Dec. 23, 1888, Vincent van Gogh mutilated his ear. That insane act is the most celebrated case of artistic temperament. But why he did he have his crisis then?

Journalist and Van Gogh scholar Martin Bailey has published an intriguing new clue.

The traditional explanation is that Van Gogh's fraught relationship with Gauguin, who had been sharing his small house in Arles, France, for the previous two months, was the trigger; in particular, Gauguin announced he was leaving.

But Bailey, writing in the Art Newspaper, has found evidence pointing in a different direction. It's contained in the Van Gogh painting "Still Life With a Plate of Onions."

Shortly before Christmas, Vincent's brother, Theo, asked a Dutch woman, Jo Bonger, to marry him. In surviving letters, Theo first mentions talking about his engagement with his brother after the ear incident, when Vincent was recovering in the hospital. It now seems that Vincent might have been informed by mail a few days earlier and that Theo's happy news helped, at least, to push him over the edge....