Alan Bissett, novelist and playwright

BEFORE making a documentary, I had an idea of Robert Burns in my head from popular myth. I have always admired Burns, but it is like people who say they are into Queen but have Greatest Hits I and II, rather than the numerous albums. That's how I thought of Burns: I knew the greatest hits, but I had never investigated deeply into his work.

How do you get inside the mind of a man that has been dead for hundreds of years? It's an interesting question and one that been pursued through the ages. There is a story about how when his wife Jean Armour died, they opened up his tomb to put her in beside him, and some chancers took the opportunity to steal Burns's skull in the middle of the night.

A plaster cast was made and taken to a phrenologist to have it analysed to try to find out what made Burns tick. We now recognise that as bogus science but at the time [in the 1800s] they took it very seriously. With modern methods of analysis, however, we can look at his language and how it suggests certain excitements in the brain.

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The scientist and literary scholar Moira Hansen used textual analysis to posit the theory that Burns might have been bipolar. If you look at certain episodes in his life, he goes through these periods of manic activity when he is almost bursting with joy, happiness, energy and is very vivacious. That is the Burns of legend we know, the roustabout with a drink in his hand and a woman on his arm.

But Burns also has periods of intense, black depression where he can hardly lift his head off the pillow and doesn't want to face the world. Through a modern lens we understand that could suggest certain depressive or bipolar tendencies. We can't be exact about these things because we don't have the man in front of us to study, but through analysing periods of his life, what he has said about himself and his use of language, we can make certain educated guesses.

There is a more complex and less likeable side to him. Burns was a man of flesh and blood. He had a great nobility to his character. He believed in democracy and freedom. You could argue in some ways he was a proto-socialist and that he was even a feminist because he believed in the rights of women. But, at the same time, he had a phallus and often that was the thing that was driving him.

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It was a surprise to find that his politics are that bit harder to pin down than I previously thought. Burns had to play this game where, because he is an exciseman, he must outwardly show deference while sending a wee code to the audience about some of his more radical sympathies. Sometimes it is not easy to work out what is the mask and what is the real Burns.

Inside the Mind of Robert Burns is on BBC Scotland, Tuesday, 10pm