Dan Brown's Inferno is doing wonders for Dante and the artists who have illustrated him. For instance, the other day a story in the Observer about the thriller writer's gift to tourism in Florence was illustrated with a painting by Domenico di Michelino in the city's cathedral.

In this picture, which dates from around 1465, the medieval poet Dante Alighieri stands, a red-robed colossus, revealing his poem The Divine Comedy to the city of Florence which he dwarfs. The title of Brown's new novel and its "symbological" codes refer to the first of three books that constitute The Divine Comedy: they are Inferno, Purgatorio and Paradiso.

In the cathedral painting, Dante gestures to the three worlds of the afterlife his poem describes – they have materialised in front of Florence, to show its people the moral choices they face.

You're going to reap just what you sow, as Lou Reed said, and this painting illuminates the consequences of our actions, according to Dante. The Divine Comedy is the supreme cultural expression of Christianity. If you commit unforgivable sins you will go to Hell, the fiery pit whose levels of increasingly ingenious punishments are acutely imagined in Inferno. If you are not quite as derelict you will have a chance after death to work your way up Mount Purgatory to reach Paradise, the realm of ethereal bliss.

Dante, writing in exile at the start of the 14th century after he fell foul of the Florentine republic's bitter factional struggles, wanted to give Christendom its answer to the ancient epic poet Virgil. He is guided through the infernal realm by Virgil himself – and Dante's poem records what they saw there, as if it were a true memoir. It is the most precise piece of visionary writing in European literature.

This hallucinatory quality has always inspired artists.

While a 15th-century painting was illuminating the Observer, a feature about Dan Brown in the Sunday Times (pay wall) included Gustave Doré's mesmerising 19th-century illustrations for Inferno. Doré gives Dante an inky darkness and romantic horror. He makes us feel the weight of the cavernous Earth that encloses this hopeless realm, the fact that we are looking into the grave, and beyond.

Doré was following a fashion for Dante in 19th-century French art. In his 1822 painting The Barque of Dante, Delacroix shows Dante and Virgil being ferried across hellish waters in which lost souls struggle, while in Ugolino and His Sons, sculptor Jean-Baptiste Carpeaux portrays the most horrible of all images in Dante: Count Ugolino was walled up with his children in a tower in Pisa and left to starve. Dante leaves the story's ending horribly ambiguous – it seems that after the little boys died, the starving Ugolino ate them. As revenge, he chews on his captor's head for all eternity.

Dante has inspired so many artists – from Rodin to Robert Rauschenberg. But my favourite has to be Sandro Botticelli.

When Botticelli set out to illustrate Dante in Florence in the late 15th century, he resisted the lurid imagery the poet may seem to call for. Or rather, while he meticulously records every horror, he uses a calm graphic style that gives his drawings a fresh and direct feel of eyewitness truth. His illustrations are so authoritative that the first time I saw them in an exhibition in Rome, I almost felt tempted to become a Roman Catholic. For Botticelli, alone among artists, makes Paradiso as fascinating as Inferno.

Give yourself a treat this summer. Read Dan Brown; why not. But also read Allen Mandelbaum's Everyman translation of The Divine Comedy that is illustrated with Botticelli's wonderful drawings.