[2][3] The Doors of Perception provoked strong reactions for its evaluation of psychedelic drugs as facilitators of mystical insight with great potential benefits for science, art, and religion.

While many found the argument compelling, others including German writer Thomas Mann, Vedantic monk Swami Prabhavananda, Jewish philosopher Martin Buber, and Orientalist scholar Robert Charles Zaehner countered that the effects of mescaline are subjective and should not be conflated with objective religious mysticism.

[6] Although personal accounts of taking the cactus had been written by psychologists such as Weir Mitchell in the US and Havelock Ellis in the UK during the 1890s, the German-American Heinrich Klüver was the first to systematically study its psychological effects in a small book called Mescal and Mechanisms of Hallucinations published in 1928.

In 1936 he told TS Eliot that he was starting to meditate,[14] and he used other therapies too; the Alexander Technique and the Bates Method of seeing had particular importance in guiding him through personal crises.

[16] He first became aware of the cactus's active ingredient, mescaline, after reading an academic paper written by Humphry Osmond, a British psychiatrist working at Weyburn Mental Hospital, Saskatchewan, in early 1952.

Osmond's paper set out results from his research into schizophrenia, using mescaline that he had been undertaking with colleagues, doctors Abram Hoffer and John Smythies.

[19] For the Canadian writer George Woodcock, Huxley had changed his opinion because mescaline was not addictive and appeared to be without unpleasant physical or mental side-effects.

[22] In a second letter on Saturday, 19 April, Huxley invited Osmond to stay while he was visiting Los Angeles to attend the American Psychiatric Association convention.

[24] Osmond arrived at Huxley's house in West Hollywood on Sunday, 3 May 1953, and recorded his impressions of the famous author as a tolerant and kind man, although he had expected otherwise.

[27] The experience started in Huxley's study before the party made a seven block trip to The Owl Drug (Rexall) store, known as World's Biggest Drugstore, at the corner of Beverly and La Cienega Boulevards.

"[31] The title was taken from William Blake's poem The Marriage of Heaven and Hell: If the doors of perception were cleansed every thing would appear to man as it is: Infinite.

Huxley writes that he hoped to gain insight into extraordinary states of mind and expected to see brightly coloured visionary landscapes.

He feels he understands the Hindu concept of Satchitananda, as well as the Zen koan that, "the dharma body of the Buddha is in the hedge" and Buddhist suchness.

[40] Reflecting on the experience afterwards, Huxley finds himself in agreement with philosopher C. D. Broad that to enable us to live, the brain and nervous system eliminate unessential information from the totality of the 'Mind at Large'.

[43]) In summary, Huxley writes that the ability to think straight is not reduced while under the influence of mescaline, visual impressions are intensified, and the human experimenter will see no reason for action because the experience is so fascinating.

[44] Temporarily leaving the chronological flow, he mentions that four or five hours into the experience he was taken to the World's Biggest Drug Store (WBDS), where he was presented with books on art.

In one book, the dress in Botticelli's Judith provokes a reflection on drapery as a major artistic theme as it allows painters to include the abstract in representational art, to create mood, and also to represent the mystery of pure being.

[46] Cézanne's Self-portrait with a straw hat seems incredibly pretentious, while Vermeer's human still lifes (also, the Le Nain brothers and Vuillard) are the nearest to reflecting this not-self state.

He reflects that spiritual literature, including the works of Jakob Böhme, William Law and the Tibetan Book of the Dead, talks of these pains and terrors.

Huxley's 'aesthetic self-indulgence' and indifference to humanity would lead to suffering or stupidity; Mann concluded the book was irresponsible, if not quite immoral, to encourage young people to try the drug mescaline.

"[63] For Steven J. Novak, The Doors of Perception and Heaven and Hell redefined taking mescaline as a mystical experience with possible psychotherapeutic benefits, where physicians had previously thought of the drug in terms of mimicking a psychotic episode, known as psychotomimetic.

[65] Huxley's friend and spiritual mentor, the Vedantic monk Swami Prabhavananda, thought that mescaline was an illegitimate path to enlightenment, a "deadly heresy" as Christopher Isherwood put it.

Martin Buber, the Jewish religious philosopher, attacked Huxley's notion that mescaline allowed a person to participate in "common being", and held that the drug ushered users "merely into a strictly private sphere".

"[66] Robert Charles Zaehner, a professor at Oxford University, formed one of the fullest and earliest critiques of The Doors of Perception from a religious and philosophical perspective.

[67] Zaehner expanded on these criticisms in his book Mysticism Sacred and Profane (1957), which also acts as a theistic riposte to what he sees as the monism of Huxley's The Perennial Philosophy.

[74] Quoting St Paul's proscriptions against drunkenness in church, in 1 Corinthians xi, Zaehner makes the point that artificial ecstatic states and spiritual union with God are not the same.

[78] Professor of religion and philosophy Huston Smith argued that Mysticism Sacred and Profane had not fully examined and refuted Huxley's claims made in The Doors of Perception.

Acknowledging that personality, preparation and environment all play a role in the effects of the drugs, Huston Smith draws attention to evidence that suggests that a religious outcome of the experience may not be restricted to one of Huxley's temperament.

[84] For Philip Thody, a professor of French literature, Huxley's revelations made him conscious of the objections that had been put forward to his theory of mysticism set out in Eyeless in Gaza and Grey Eminence, and consequently Island reveals a more humane philosophy.

He decided his previous experiments, the ones detailed in Doors and Heaven and Hell, had been "temptations to escape from the central reality into false, or at least imperfect and partial Nirvanas of beauty and mere knowledge.