A new theory has emerged that may be the answer to the mystery of why Van Gogh cut off his own ear.

On Christmas eve of 1888, Vincent van Gogh chopped his left ear off with a razor. And no one knows why.

Author Martin Bailey has come up with a new theory that may provide the reason for this bizarre behaviour. Bailey found off that Gogh mutilated himself upon learning of his brother's engagement while researching for his book called 'Studio of the South: Van Gogh in Provence'.

Gogh's brother and close friend, Theo had announced to him via a letter that he was getting married. Bailey says in the book that Gogh was afraid that he'd lose his closest companion.

“He was equally worried that his brother might withdraw the financial support which had enabled him to devote his life to art. All this was threatened by the unexpected appearance of a fiancée.”

This theory is mostly based on a letter which was delivered to Gogh the day before he chopped off his ear. The letter is lost, so there is no concrete evidence as regards the contents of the letter.

However, Bailey seems to have uncovered enough information to deduce that Theo's letter conveyed his plans to get married.

He told CNN: “It’s a matter of putting all the clues together. We don’t have that letter, but in another one Van Gogh sends in January, he mentions receiving money from his brother on the 23rd of December.”

So it is certain that Gogh received a letter from Theo on December 23, 1888. In addition, his fiancee, Johanna Bonger, received a congratulatory telegram of congratulations from her elder brother on the same day.

It is therefore reasonable to infer that Johanna's brother, Henry and Theo's brother, Vincent were informed of the upcoming nuptials at the same time.

Therefore, it is quite plausible that Vincent Van Gogh who was already struggling with mental illness was so disturbed by the news that he chopped off his left ear in a fit.

Gogh was emotionally and financially dependent on his brother, and so he was deeply disturbed by his engagement, especially as he had not sold any painting at all.

Bailey says: “It was fear that pulled the trigger and led to the breakdown. Fear of being abandoned in both an emotional and financial way.”

Before Bailey's theory, the leading theory was that he snapped and suffered a psychotic breakdown after a turbulent fight with his close friend who was also a painter, Paul Gauguin.

However, it is quite possible that a combination of his brother's wedding announcement and the fight with his friend led to the artist chopping off his ear.