Time, the Collaborator

In May 1888, Vincent climbed the hill of Montmajour outside Arles again and again, drawing the ruins of the medieval abbey. They were his first ambitious works in the South.

Today several sheets of that series lie in the storerooms of the Van Gogh Museum, assigned by researchers to a cruel category: images that can no longer credibly be read. Only the faintest traces remain on the paper, like a memory rinsed in water.

But two records prove they were once something else entirely. Theo's widow, Johanna, inventoried the collection twice, in 1907 and 1909, and next to these drawings she noted their colour: violet. Earlier still, at a Rotterdam exhibition in 1901, a critic singled out for praise five sheets drawn in purple ink.

The violet now survives in just two places: in the narrow margins once protected by a passe-partout, and deep in the paper's fibres — where, in 2005, Raman spectroscopy detected an organic compound derived from aniline.

Aniline: the synthetic dye born of coal tar in 1856, the most fashionable source of colour in the later nineteenth century. Violet, mauve, purple — the new spectrum of the Impressionist decades. These inks were brilliant, free-flowing, cheap, and had one flaw the manufacturers knew from the start: exposed to light, they die.

Vincent chose them anyway. He wanted the brilliance of the moment, and time collected the interest.

The universal browning

The violet of Montmajour is the extreme case, not an isolated one. His drawings as a body have been undergoing a slow chemical rewriting.

Most widespread is the browning. His pen drawings from Nuenen were made with iron-gall ink — a medium in use for eight centuries, with a notorious temperament: deep black or near-black when fresh, it oxidises over the years toward red-brown and grey-brown. Of all the "brown-toned" Nuenen drawings we see today, not one was brown when it left his pen.

And it is precisely this fading that gave away a secret.

On sheets like Pollard Birches, the ink lines are everywhere accompanied by extensive graphite pencil work — which, against today's brown-dominated image, looks illogical, out of key. But restore the ink to black in your mind's eye and everything resolves: black ink and grey graphite were a deliberately paired timbre, one carrying the skeleton, the other carrying volume, ground and shadow.

From this, a long-overlooked fact can be reconstructed: in his hands, pencil was never mere underdrawing. Draughtsmen ordinarily erase their pencil before the ink does its work; he almost never did — graphite was a full member of the composition, one voice in his "painting in black." That working method is visible today with such clarity precisely because the ink faded. The scholars studying him reach for a striking word: such mutations are almost "serendipitous."

The blue of Paris

In early 1887 in Paris he drew a series of cityscapes and conducted a colour experiment almost nobody knows about — because the ground it was conducted on no longer exists.

A Guinguette, Window in the Bataille Restaurant, Boulevard de Clichy: all three were drawn on blue-grey paper. Today that blue has all but vanished; the sheets have discoloured to a range from dirty yellow to yellow-brown, with only threads of the original colour surviving at the edges.

In 2005, researchers used computer simulation to restore the paper's colour, and the hidden experiment came back into view: on blue paper he had drawn in blue chalks of varying depth — blue on blue, a simultaneous contrast — then dropped in a few strokes of complementary orange to spark it. This was exactly the colour science he was drilling in his paintings at the time, transposed to paper. Boulevard de Clichy even has a painted counterpart, executed over a ground of pale blue.

Set the reconstruction beside the current state: against the dirty yellow, the blue chalk lines look coarse and abrupt, every harmony gone. If you did not know the paper had been blue, you would take this for a clumsy drawing. Discoloured paper is not just a loss; it can demote a rigorous experiment to an apparent failure.

The evaporated blossom

The saddest case is in Arles.

In April 1888 he painted Pink Peach Trees in memory of Anton Mauve, the painter cousin-in-law who had once taught him — "Souvenir de Mauve" written on the frame. He made a watercolour version of the picture on paper.

The pink of the blossoms was a synthetic pigment of the day: tender, and as short-lived as the aniline violet. A century and more later: in the oil, the blossoms at least survive as clusters of white impasto — the colour gone, the body of the flowers still on the branch. But a watercolour has no impasto. On the paper version, the pink has evaporated to barely a trace; the branches stand bare, and the surviving white flecks float where the sky is, looking no longer like blossoms, but like clouds.

A painting of spring, edited by time into winter.

Creases are records too

Not every material change is a loss; some are evidence.

In The Hague he favoured a heavy, rough watercolour paper (the French call it torchon), because he had taken to working on wetted sheets, taming graphite and chalk with water. The result: blistered, puckered paper — an unevenness that is itself a fossil of his working method. When later restorers tried to press these drawings flat, the scholars were unequivocal: that is a mistake. The creases are not damage; they are the archive of a procedure.

On Worn Out from the same period — the almshouse old man with his head in his hands — the sheet still shows a halo of fixative staining around the figure, and an odd sheen to the graphite: he had brushed the pencil work with milk, a household trick for killing graphite's shine. Even the model can be named: Adrianus Zuyderland, a resident of the old people's home who sat for him dozens of times in The Hague. On a single sheet, from the milk to the stain to the grid lines of the perspective frame, every fingerprint of the procedure survives.

Why him, of all artists

Every work on paper from the nineteenth century fears the light, but his drawings have suffered conspicuously more. The researchers give two reasons, which together approach irony.

First, his drawings mattered too much. For most painters of his generation, drawing was preparatory, an appendage of painting; for him, the drawings stand as equal partners to the canvases — that is the consensus of art history. And so for more than a century, exhibitions everywhere have wanted to borrow them. Every showing is a dose of light.

Second, he loved pen and ink above all — and ink is the medium most sensitive to light. No other modernist placed so fragile a technique so near the centre of his creative process. Among artists, the vulnerability of his work on paper compares only to that of a watercolour specialist like Cézanne.

The degree to which he is seen has set the speed at which he is consumed.

The prisoners and the light

In 1894 the Belgian architect Henry van de Velde visited Johanna and was shown the still-unframed drawings. What he later wrote remains the best description of those sheets:

"Those random sheets, unframed, rough-edged, were so charged with electricity that as we took each in turn they seemed intent on wriggling out of our hands — like prisoners long immured in darkness, frantic to escape into the light of day."

Read today, the sentence carries an irony van de Velde could not have foreseen: they did escape into the light — and it is the light that has been killing them.

So "seeing the original" needs redefining here. The sheet you see in a museum is the current frame of a chemical reaction that has been running for a hundred and thirty years and has not stopped. The sheet Vincent drew — the violet Montmajour, the blue Paris, the pink blossom — exists only in an afternoon of 1888, in Johanna's inventory, in the descriptions in the letters, and in the few molecules a spectrometer can still retrieve from the fibres.

This is not all bad news. The fading of the ink made the pencil's voice audible for the first time; the puckered paper preserved the scene of his wet-working method; the margins under the passe-partout sealed away the violet as physical proof. Time has destroyed part of the original, and in the same motion testified for another part.

It is not only a destroyer. It is the last collaborator these drawings have — one that never signs.

On sources Material for this essay is drawn from Vincent van Gogh: The Drawings (Metropolitan Museum of Art / Van Gogh Museum, 2005), principally Sjraar van Heugten's essay "Metamorphoses: Van Gogh's Drawings Then and Now" (including the computer reconstructions of the Paris papers), and the materials reports by Marjorie Shelley and Silvia A. Centeno (X-ray fluorescence, Raman spectroscopy, infrared reflectography). Johanna van Gogh-Bonger's inventory notes and the 1901 Rotterdam review are cited in the same volume.