An exhibition at London's Royal Academy seeks to deepen our understanding of the post-Impressionist master Vincent Van Gogh by displaying not only his paintings and drawings, but many of his letters.

The Dutch painter wrote hundreds of letters during a productive career as an artist, most of them to his brother Theo who was an art dealer who supported him.

The Real Van Gogh: The Artist and his Letters, from Saturday to April 18, follows a 15-year research project into Van Gogh's correspondence by the Van Gogh Museum and the Huygens Institute of the Royal Netherlands Academy of Arts and Sciences.

On display at what is predicted to be a major blockbuster exhibition are over 35 original letters, rarely displayed in public due to their fragility but which provide context for many of the 65 or so paintings hanging alongside them. The letters which contain the mundane - as in his description of a particular kind of pencil - and the poetic - as when he describes the waters of the Mediterranean as "like a mackerel" and "always changing" - challenge the notion of Van Gogh as an erratic and tortured genius.

"The popular view of him is that he was this kind of crazy, unreflective artist who just painted very quickly and very spontaneously," said curator Ann Dumas.

"He did paint very quickly. But a great deal of thought and preparation had gone into his work even before he put paint on canvas," she said.

Although he cut off part of an ear, committed himself to an asylum and ended his own life aged 37, Van Gogh was engrossed in his art and prepared to work hard to master techniques of perspective, colour and painting the human form.