The letters he wrote to his friends and family have long been recognised as much more than the mere jottings of a painter but as a great literary achievement in their own right. As Vincent himself remarked to his younger brother Theo, “…drawing in words is also an art”.

Most of us have only caught glimpses of the expressive power of Van Gogh’s writings, but a massive new edition of the letters now allows anyone to appreciate this side of his work in full.

The edition has been produced in traditional book form (in six volumes) but the prime publication is a superb new website (www.vangoghletters.org), freely available to all users.

The web edition brings together all the original texts with completely new translations, annotations and is illustrated with all the relevant works of art. It is an amazing new resource which will, quite simply, transform our view of Van Gogh and his achievement as both artist and writer.

When I joined the Van Gogh Museum as director back in 1997, work on this new edition was already underway. At the museum we came to regard this key project as something of a rescue mission.

On one level, the small dedicated team of experts were rescuing Van Gogh’s letters from the accumulated inaccuracies and misinterpretations of all the various previous editions that had been produced since his sister-in-law first published the correspondence in 1914.

With utter precision and painstaking research, the goal was to publish Van Gogh’s letters as he wrote them, stripping out errors in transcription and removing the embellishments in translation, both intentional and unintentional, that had gradually come to distort and impair our view of his writings.

This process of purification was in itself no easy task. The majority of the 902 surviving letters are held in a vault in the basement of the Van Gogh Museum, where the letters team spent many years working through each document word by word.

Many of the letters were written on cheap, tissue-thin paper, often using an ink which had corrosive properties and, over the years, started to eat into and even partially obliterate what are now incredibly fragile documents.

Van Gogh wrote most of them either in his native Dutch or in his simple yet sometimes peculiar, self-taught French.

Deciphering these texts, often written at top speed in the full flow of emotion and passion, can be difficult enough but the researchers and the group of translators who worked with them had to come up with accurate equivalents for the artist’s very individual style as author.

Alongside the effort to regain the integrity of the original texts there was a vast amount of detective work to explain and clarify the subject matter of the letters.

There have been some major new discoveries, including 20 new letters that have not been previously published outside Holland. But the value of the new edition is also in the countless new insights that have been brought to light. Very few details seem to have escaped their attention.

I remember, for example, the researchers enthusiastically showing me a tiny piece of seaweed that Van Gogh had attached to a letter to his brother Theo in which he describes a walk along the beach at Ramsgate. Van Gogh stayed briefly in the English seaside town in 1876 during his short-lived career in teaching.

On the new website the researchers have identified the actual species of moss animal (not seaweed) that Van Gogh sent to Theo, even noting how “three miniscule mussels” also made the journey through the post to Holland with this letter.

Somehow, the scientific accuracy of the identification serves to underline the poignancy of this touching souvenir. For the first time, the new edition is fully annotated, providing invaluable background information on the people, the places or the art works that fired Van Gogh’s imagination.

All the 600 or so people that he mentions have been identified and the 2000 art works that he refers to have been traced and most of them are illustrated alongside the relevant letters on the website.

The many hundreds of quotes that he uses, sometimes directly, sometimes reworked in his own words, were tracked down. Van Gogh was a passionate reader and his letters are brimming with excited references to the Bible, the classics, Shakespeare and famous works of modern French and English literature, such as Emile Zola and Charles Dickens, through to obscure and long-forgotten contemporary authors whom he admired.

For Van Gogh, literature was as real and evocative as painting, and he found support and endorsement for his own endeavours in the work of his favourite authors.

As rescue efforts go, this one was a long, drawn-out affair. A project that was originally scheduled to take five years has eventually taken 15 years to publish.

If I have one regret about leaving the Van Gogh Museum for the National Galleries of Scotland, it is that I was not able to see this project through to completion and to associate myself with a great piece of scholarship by at least providing a foreword.

It has taken three directors of the museum to see this edition published, but it has been worth the wait and the monumental effort because it is not just the original intentions of Van Gogh as a writer that have been reclaimed but his character as an artist that has been restored and refreshed.

Successive generations of art lovers have grown used to the lazy cliché of Van Gogh as the crazed and suffering genius, a spontaneous, unworldly victim whose art was the by-product of insanity and despair.

Who could forget Kirk Douglas as Van Gogh in the 1956 movie Lust for Life, battling with Gauguin (Anthony Quinn), munching on paint or lashing out at crows as he tries to complete his final painting?

For many years the letters have been plundered for evidence to support an over-simplified narrative of a tragic life. Contrary to the popular myth, the complete letters reveal the clarity and the consistency that lies behind Van Gogh’s brief career as an artist as well as the depth of his knowledge.

There is plenty of exuberance and there is no shortage of melancholy and even despair, but ultimately it is the exceptional lucidity of his thought that comes through. In many respects he emerges as a very rational man.

In his letters Van Gogh tried to make sense of his life, his mission and the role that his art could play in society. Having abandoned a career as a teacher and evangelist and having turned his back on conventional religion, he became convinced that his art had a purpose to help reveal what was extraordinary in an ordinary, everyday world.

His correspondence reveals his search to leave mankind, as he put it, “a certain souvenir in the form of drawings and paintings in gratitude – not done to please some (artistic) movement or other but in which an honest human feeling is expressed”.

Vincent van Gogh: The Letters – The Complete and Annotated Edition, edited by Leo Jansen, Hans Luijten and Nienke Bakker, Thames and Hudson.

www.vangoghletters.org