Vincent on Vincent: New edition Van Gogh letters give searing insight into artist's breakdown

Even today, when Vincent van Gogh's international reputation is higher and wider than ever, we have intense difficulty understanding how he managed to paint such a sustained series of masterpieces. After mutilating his ear and struggling to retain his sanity in an asylum, this vulnerable young Dutchman dreaded the sudden onset of each new bout of epileptic seizure. But somehow, he carried on painting for another turbulent year, producing his finest work before succumbing to suicide in 1890.

Now, with the publication of an unprecedentedly complete edition of his letters, we are able to get closer to Van Gogh's struggle. Some of these eloquent letters, embellished with his urgent drawings, will be displayed in the Royal Academy's exhibition The Real Van Gogh, opening this month. Mostly written to his younger brother Theo, whose devoted care and financial assistance proved crucial, they reveal just how dramatically Van Gogh veered from panic and hopelessness to incisive, stubborn resolve and back again. As early as September 1883, seven years before he killed himself, Van Gogh confessed to Theo that, "because I have a need to speak frankly, I can't hide from you that I'm overcome by a feeling of great anxiety, dejection, a 'je ne sais quoi' of discouragement and even despair, too much to express. And that if I can find no consolation for it, it might all too easily overwhelm me unbearably."

These words proved sadly prophetic. But Van Gogh, having wisely abandoned his attempts to become an art dealer and a priest, developed as a painter with astonishing inventiveness and flair. Although unable to sell his work, he was sustained by its momentum even when, in May 1889, he was admitted to a mental home near Saint-Rémy-en-Provence. The attending physician, Dr Théophile Peyron, recorded on the certificate of entry that his 36-year-old patient had been "stricken by acute mental derangement, with hallucinations of his sight and hearing, which led him to mutilate himself by cutting off his ear".

The affliction was terrible enough to make Van Gogh remain in the asylum for an entire year. Even so, this illness did not prevent him from pursuing his art with a remarkable sense of discipline, concentration, audacity and, above all, passionate commitment.

Fortified by medicine, he hoped his mind would never again succumb to "indescribable mental anguish when the veil of time and inevitability seemed for the twinkling of an eye to be parted". Although Dr Peyron came to the hesitant conclusion that Van Gogh was suffering from "a state of epilepsy", he was encouraged by his patient's initial progress.

After recurrent painful nightmares during the first few weeks of his stay, Van Gogh's sleep improved, along with his appetite, and he seemed adept at discovering continual inspiration in whatever surroundings confronted him. A few weeks earlier, he had bravely asserted that: "If I had to stay for good in an asylum, I should make up my mind to it and I think I could find subjects for painting there as well." The prophecy was borne out to spectacular effect at Saint-Rémy, where he painted many of his most vibrant canvases.

Within a week of arriving at the asylum he was hard at work on paintings of the garden, one of which turned into a superlative image called Irises. At first sight it appears a festive work, revelling in the piercing clarity of the violet-blue flowers as they thrust and wave with an exuberance worthy of a Hokusai print. After a while, though, more disturbing elements demand attention. The irises and their blaring green leaves fill the canvas with insistent movement, as if jostling for room in the confined picture-space. They crowd the solitary white flower in their midst, provoking the suspicion that Van Gogh equated their clamorous behaviour with the more disturbed patients confined inside the asylum's walls.

In one letter, he told Theo that, "There is someone here who has been shouting and talking like me all the time for a fortnight; he thinks he hears voices and words in the echoes of the corridors, probably because the nerves of the ear are diseased and too sensitive." He explained to his brother that, "as there are more than thirty empty rooms" at the asylum, he had been given "one to work in". He lost little time in hanging on its walls his unframed works, one of which can be seen in a gouache study of this new studio. He longed to animate the whole asylum with his art, telling Theo that "it would be splendid to hold an exhibition in all the empty rooms, the large corridors".

Van Gogh was irrepressible as an artist for much of his stay. Towards the end of May, he described his excitement over the view from his bedroom, where "through an iron-barred window I see a square field of wheat in an enclosure, a perspective like Van Goyen, above which I see the morning sun rising in all its glory".

Soon after Dr Peyron allowed him to work in the field, he began an extended sequence of views that amount to the finest series of paintings he produced at Saint-Rémy. The first canvas, Mountainous Landscape Behind the Asylum, is one of the most outspoken in use of nature as a metaphor for his own emotional condition. The turbulence of the wheat, heaving in its enclosure like an angry sea, surely refers to Van Gogh's view of his plight within the institution's walls. He described the painting to Theo on 9 June, explaining that the foreground contained "a field of wheat ruined and hurled to the ground after a storm".

Towards the end of June, he started work on a painting called The Reaper, and brought it to virtual completion before suffering a serious breakdown. The choice of theme may well have reflected an awareness that a mental crisis was imminent, for when Van Gogh resumed work on the picture in early September he informed Theo that, "I see in this reaper – a vague figure fighting... in the midst of the heat to get to the end of his task – I see in him the image of death, in the sense that humanity might be the wheat he is reaping." The toiling peasant could embody Van Gogh's realisation that he was engaged in a struggle against mental illness to complete the task he had set himself as an artist. But, he insisted, "There's nothing sad in this death, it goes its way in broad daylight with a sun flooding everything with a light of pure gold."

In one mood, Vincent transformed a view of the hospital at Saint-Rémy (Trees in Front of the Entrance to the Asylum) into an ecstatic image, rejoicing in the vigour of trunks and foliage as they soared above the buildings. "I tried to reconstruct the thing as it might have been," he explained, "simplifying and accentuating the haughty, unchanging character of the pines and cedar clumps against the blue."

During the first few months of his stay, he recovered from the initial shock of other inmates screaming day and night and started talking to them, even though they were incapable of coherent replies. And he reported in a letter to his sister that, "Though there are some seriously ill here, the fear of madness that I felt has already largely disappeared."

Yet, soon after, Van Gogh suffered a gruelling attack while at work in the foothills near the asylum. The onset of a mistral, blowing a half-finished painting off its perch, seems to have precipitated his collapse. A protracted fit of yelling left his swollen throat acutely painful for days, and he even attempted suicide by gulping down his own paints. Nightmares and hallucinations dogged the artist. Hidden away in his room, where he struggled to cope with this alienation by working harder than ever on self-portraits filled with an unbearable sense of strain, Van Gogh felt tormented. "If one could resign oneself to suffering and death, surrender one's will and love and self!" he wrote. "But I love to paint, to meet people, to see nature."

Eventually, in April 1890, he announced to Theo that his period at the asylum should be terminated. But he could not bear the thought of leaving the South, with all its fertile inspiration, and going north to live with Dr Gachet, an avid collector of Impressionist art.

Auvers-sur-Oise, where Gachet had a house, was only an hour from Paris, and at first Van Gogh managed to paint some outstanding images. But this final burst of blazing productivity could not be sustained. Just over two months after he left Saint-Rémy in May 1890, he wrote a letter to Theo that sounds purposeful enough – but one passage is sadly revealing: "I'd like to write to you about many things, but first the desire has passed to such a degree, then I sense the pointlessness of it all."

Four days later, Van Gogh went out into the fields and clumsily shot himself in the chest with a revolver. His arduous attempts to recover mental stability with medical help had failed, and he died two days later. On his deathbed, when the distraught Theo asked him why he had decided to commit suicide, Van Gogh only managed to reply with another, equally anguished question: "Who would imagine that life could be so sad?"

The Real Van Gogh opens on 23 January at the Royal Academy, London, W1: royalacademy.org.uk. 'Vincent van Gogh – The Letters' is published by Thames & Hudson