KENT, England — The world’s oldest psychiatric hospital is tucked away in a gently faded London suburb. It’s true that Bethlem Royal Hospital’s current incarnation is several sites removed from its original 13th-century home near Bishopsgate. But the hospital’s administration runs in a continuous line from the Priory of the New Order of Our Lady of Bethlehem all the way to the present-day National Health Service. Bethlem’s famous nickname “Bedlam” has migrated into English as a synonym for chaos and confusion. If, like me, you have a mental illness, the institution’s name can bring to mind visions of purges, bleeding, and patients in chains — not the most comfortable image for a hospital which exists to alleviate mental distress.

Rather than shy away from its past, Bethlem meets it head on in one of London’s most compelling small galleries. Bethlem Museum of the Mind is the hospital’s onsite gallery space, whose mandate is to curate exhibitions about the intersection of art and mental healthcare. What that means in practice is hosting exhibitions which grapple with Bethlem’s chequered legacy of healing, coercion, and shame.

The museum’s latest exhibition Brilliant Visions: Mescaline, Art and Psychiatry plunges into the murky world of psychosis and psychedelics. It’s also a celebration the 100th anniversary since Ernst Späth first synthesized mescaline, influencing a generation of spiritual seekers, artists, and psychiatrists. Unsurprisingly, it’s psychiatry which takes the centre stage at Bethlem, particularly the infamous Guttman-Maclay experiments. In the 1930s, the two doctors gave mescaline to “psychotic” patients (a dated term for what was likely schizophrenia) and asked them to make art “to explain themselves.”

Unsatisfied with the results, the doctors recruited Surrealist painters to take the drug, in the hope that mescaline would produce an “artificial psychosis.” The result was an experimental collection of paintings in fragmented colors and shapes. The swirling designs in vibrant colors show how much the fashion choices of the 1960s owe their origin to psychedelics. The most striking among them is “Mescaline Painting — Blue & Red Abstract” (1938) by an anonymous participant, where energetic strokes of paint are set against a vivid blue background.

Although Bethlem is a relatively small gallery space, Brilliant Visions is intensely ambitious. The single room manages to devote space to the combined history of psychiatry, mescaline, and art. While the overall narrative comes together well, the effect is occasionally disjointed and the contemporary mescaline paintings tread familiar ground with psychedelic patterns. More interesting are the historical artefacts, like doodles by volunteers on mescaline and the cabinet of public letters in response to the politician Christopher Mayhew’s article on its effects. “Dear Sir,” reads one from a man who had suffered a botched operation, “Your article in The Observer was of special interest to me because I am convinced that, nearly forty years ago, I was outside time and space in the sense that I was dead.”

“Snakes and Bodies and Sharks” (1936) by Kathleen Heppner is the only artwork that was likely made by one of Guttman and Maclay’s original patients. Her painting is dominated by a large purplish-brown oval with heavy cracking paint. It takes a moment to realize that the reason why the painting is brown is the overlap of vivid reds and blues which appear to have been smeared on with her fingers. An exhibition label explains that the title is a reference to Heppner’s hallucinations, which are supposed to be represented in the painting alongside what she described as “Tigers or Dogs or Doves, two shining black eyes … [and] a flying moon or a face.”

There’s a clear discrepancy between the energy of her description, the painting style, and the end result. It makes me wish that Guttman and Maclay had been more interested in listening to Heppner about what caused that breakdown in communication. The absence of other artwork by patients is noticeable and begs the question why some paintings were more worth preserving and displaying than others — particularly because some surviving Surrealist paintings are clumsy and flat, more interesting as historical artefacts than art.

The missing paintings bring to mind the debate about “outsider art,” a controversial term for the artist Jean Dubuffet’s concept of art brut (raw art). Dubuffet was interested in art produced outside the boundaries of officially sanctioned aesthetic culture, notably by children, prisoners, and patients in psychiatric hospitals. Today, “outsider art” is used to label work by self-taught artists and continues to be strongly associated with mental illness.

One of the questions implicit in the outsider art debate is which sources of authority get to determine professionalism in art? Dubuffet himself hoped to democratize art, setting aside intellectual pretences to reach a wider audience. However, the grouping of people with a mental illness alongside children has an unsettling ring of condescension. All too often minority groups like people with a mental illness are excluded from the magic circle of artistic legitimacy. Either that, or they’re relegated to a fetishized sideshow, not unlike the way Bethlem’s patients were once displayed to the public.

Brilliant Visions doesn’t examine this debate because its focus is, understandably, on mescaline. Nevertheless, the exhibition brings to mind uncomfortable questions about power and prejudice. It makes for an interesting companion piece to Bethlem’s permanent exhibition in the adjacent room. Here, in addition to work by artists like Richard Dadd and Cynthia Pell, there’s a considered debate about the ethics of how we conceptualize mental illness.

In some ways, Bethlem is a lesson in how gallery space influences the interpretation of its contents. The Museum of the Mind overlooks grounds which are testament to 800 years of trying to understand mental illness. Brilliant Visions encapsulates a small portion of that effort, to poignant effect.

Brilliant Visions: Mescaline, Art, Psychiatry is on view at Bethlem Museum of the Mind (Bethlem Royal Hospital, Monks Orchard Road, Beckenham, Kent) through August 21. The exhibition is co-curated by Mike Jay and Kate Tiernan.