In 1908, Paul Klee, struggling as a painter, saw his first van Gogh canvas at a gallery in Munich. The Dutchman’s genius was at once clear to him; so, too, and inseparably, was his madness. ‘Pathetic to the point of being pathological,’ Klee wrote, ‘this endangered man’ has a brain ‘consumed by the fire of a star’. Three years later, and shortly before joining them himself, Klee reviewed a show of works produced by the Blaue Reiter group. Once again, it was the irrational that drew his eye. ‘Neither childish behaviour nor madness are insulting words here, as they commonly are,’ Klee enthused. ‘All this is to be taken very seriously, more seriously than all the public galleries, when it comes to reforming today’s art.’

A decade later, the polymath Oskar Schlemmer, shortly to take up a teaching post at the new Bauhaus in Weimar, went to a slide show of images of the art of the insane. What he saw in Stuttgart that night stirred him to ecstasy. ‘For a whole day I imagined I was going to go mad,’ an excited Schlemmer wrote to his fiancée, ‘and was even pleased at the thought, because then I would have everything I have been wanting.’

For all that, the young Swabian spotted a problem. ‘Klee’, he went on, ‘has seen these things and is enthusiastic’; the work he and other moderns were making bore ‘surprising similarities’ to that of the mad – men such as the ‘schizophrenic master’ August Klett, who thought himself Christ and, locked for decades in an asylum, produced émaillée paintings of odd beauty with names such as Die Republik der Hähne in der Sonne hat ohne Kostüm gegessen und getanzt (‘The Republic of Roosters Ate and Danced in the Sun without Costumes’). But if the art of the moderns resembled that of the insane, then the reverse was also true. With what would turn out to be unhappy prescience, Schlemmer saw that this resemblance would one day be used as a weapon against modernism. ‘See!’ he went on, rhetorically to his fiancée. ‘They paint just like the insane!’

Between Klee’s Blaue Reiter review and Schlemmer’s letter had come the First World War. Having seen, in many cases first-hand, the insanity of the trenches, avant-garde artists across Europe found themselves moved to paint something more than reality. The Surrealists in Paris found their subject first in the irrational of the Freudian pre-conscious and then in the communitarian unconscious of Jung. In Germany, the drive was towards abstraction, so-called non-objective art. Here, particularly, the insane had a head start. ‘The madman lives in a realm of ideas which the sane artist tries to reach,’ Schlemmer wrote sadly. ‘For the madman it is purer, because completely separate from external reality.’

As he had also realised, opposition to this view in Germany was already growing. If modernists sought to redeem madness by owning it, a counter-tendency aimed more simply to eradicate it. This latter movement was led by a plodding and talentless figurative painter called Adolf Hitler. The realism ordained by Hitler was to give rise to a kind of madness beyond the wildest schizophrenic dreams of Klett. Officially prescribed art presented a fantasy world in which men were universally strapping, women subservient and pink-cheeked and children had unvarying blue eyes.

***

This parallel shift in German thinking on art and insanity is the subject of Charlie English’s compelling new book, The Gallery of Miracles and Madness. Its two principal themes, the demonising of modernist art as degenerate and the murder of the inhabitants of asylums in the so-called Aktion T4, are well enough known. Where the particular fascination of English’s book lies is in his discovery of an overlap between them.

By 1938, Schlemmer’s prediction had come woefully true. In that year, the ‘Degenerate Art’ exhibition in Munich juxtaposed a pair of self-portraits by Oskar Kokoschka with another by a man called Georg Birnbacher. The accompanying guide asked visitors to guess which of the works was by a supposed master, which by ‘an amateur, an inmate of a lunatic asylum’. ‘You will be surprised!’ the text crowed. Birnbacher was a long-term resident of the psychiatric clinic at the University of Heidelberg and a patient of Hans Prinzhorn. Prinzhorn, a brilliant psychiatrist, had been the first to recognise the extraordinary artistic talent of many of the inmates, particularly those diagnosed as schizophrenic. He had carefully collected and catalogued their work and travelled the world proselytising on its behalf. It was his slide show that Schlemmer had seen in Stuttgart in 1920.

In English’s narrative, the twin strands of Hitler’s thinking on art and racial purity draw remorselessly together. The year after the ‘Degenerate Art’ exhibition, a National Socialist couple from Leipzig wrote to the Führer, begging his permission to kill their badly disabled infant son: ‘the monster’, as his father referred to him. In July 1939, the baby became the first victim of a policy of state murder that would see the death of perhaps three hundred thousand Germans deemed ‘ballast’ and ‘useless eaters’. Some seventy thousand of these were inmates of asylums, among them many of Prinzhorn’s artist-patients.

One was Paul Gösch, who, as English notes, had had the unique and unenviable distinction of having his work included in the ‘Degenerate Art’ exhibition on two counts: as an example of professional degeneracy (at the original Munich show) and of amateur madness (when it moved to Berlin). Unusual among Prinzhorn’s stable in having trained as a professional painter, Gösch had first been incarcerated with schizophrenia in 1917. In 1934 he was moved from an asylum in Göttingen run by his brother-in-law to another, more brutal one in Teupitz. In 1940 he was taken to the killing centre at Brandenburg an der Havel to be gassed with carbon monoxide.

The same fate awaited Franz Karl Bühler, whose Blakean crayon drawing Der Würgengel (‘The Choking Angel’), used as the frontispiece to Prinzhorn’s ground-breaking book Bildnerei der Geisteskranken in 1922, proved an appalling premonition of his own end. Trained as a master blacksmith – his trio of Baroque gates had been the centrepiece of the Chicago World Fair in 1893 – Bühler was taken in March 1940 from the asylum in Emmendingen that had been his home for four decades to the castle at Grafeneck, one of the most efficient of the Aktion T4 killing centres. There, in a scene that prefigured the killings in the gas chambers at Auschwitz, he was herded into a room tricked out as a communal shower and gassed with fifty-three others as an SS doctor looked on through a spy window. Carbon monoxide kills by choking its victims. One observer at Grafeneck recalled seeing ‘patients, naked … with their mouths terribly wide open, their chests heaving’.

My only cavil about English’s book is that it is too long. For all its fascination, the awful tale it tells is in essence a micro-history, concerning at most a few dozen people who had the great misfortune to be both talented and incarcerated as mad. A tighter focus on these and less time spent on the tectonic shifts that would eventually crush them might have made The Gallery of Miracles and Madness more memorable than it already is.