“I see the true importance of LSD in the possibility of providing material aid to meditation aimed at the mystical experience of a deeper, comprehensive reality. Such a use accords entirely with the essence and working character of LSD as a sacred drug.”

Chaos and Cyber Culture (1994)

Source: LSD : My Problem Child (1980), Ch. 1 : How LSD Originated
Context: This self-experiment showed that LSD-25 behaved as a psychoactive substance with extraordinary properties and potency. There was to my knowledge no other known substance that evoked such profound psychic effects in such extremely low doses, that caused such dramatic changes in human consciousness and our experience of the inner and outer world.
What seemed even more significant was that I could remember the experience of LSD inebriation in every detail. This could only mean that the conscious recording function was not interrupted, even in the climax of the LSD experience, despite the profound breakdown of the normal world view. For the entire duration of the experiment, I had even been aware of participating in an experiment, but despite this recognition of my condition, I could not, with every exertion of my will, shake off the LSD world. Everything was experienced as completely real, as alarming reality; alarming, because the picture of the other, familiar everyday reality was still fully preserved in the memory for comparison.
Another surprising aspect of LSD was its ability to produce such a far-reaching, powerful state of inebriation without leaving a hangover. Quite the contrary, on the day after the LSD experiment I felt myself to be, as already described, in excellent physical and mental condition.
I was aware that LSD, a new active compound with such properties, would have to be of use in pharmacology, in neurology, and especially in psychiatry, and that it would attract the interest of concerned specialists. But at that time I had no inkling that the new substance would also come to be used beyond medical science, as an inebriant in the drug scene. Since my self-experiment had revealed LSD in its terrifying, demonic aspect, the last thing I could have expected was that this substance could ever find application as anything approaching a pleasure drug.

Attributed to Leary by Terence McKenna in one of his talks ( "The World and Its Double" https://terencemckenna.wikispaces.com/The+World+And+Its+Double, 11 September 1993, Nature Friends Lodge, Sierra Madre, CA), though he also stated[citation needed] Leary denied ever having said it.
Misattributed

To Robert Dreyfuss in 1964, p. 6403.
Lord Meher (1986)
Context: Tell those who indulge in these drugs (LSD, marijuana, and other types) that it is harmful physically, mentally and spiritually, and that they should stop the taking of these drugs. Your duty is to tell them, regardless of whether they accept what you say, or if they ridicule or humiliate you, to boldly and bravely face these things.

1960s, Playboy Interview (1969)

Source: LSD : My Problem Child (1980), Ch. 1 : How LSD Originated
Context: This self-experiment showed that LSD-25 behaved as a psychoactive substance with extraordinary properties and potency. There was to my knowledge no other known substance that evoked such profound psychic effects in such extremely low doses, that caused such dramatic changes in human consciousness and our experience of the inner and outer world.
What seemed even more significant was that I could remember the experience of LSD inebriation in every detail. This could only mean that the conscious recording function was not interrupted, even in the climax of the LSD experience, despite the profound breakdown of the normal world view. For the entire duration of the experiment, I had even been aware of participating in an experiment, but despite this recognition of my condition, I could not, with every exertion of my will, shake off the LSD world. Everything was experienced as completely real, as alarming reality; alarming, because the picture of the other, familiar everyday reality was still fully preserved in the memory for comparison.
Another surprising aspect of LSD was its ability to produce such a far-reaching, powerful state of inebriation without leaving a hangover. Quite the contrary, on the day after the LSD experiment I felt myself to be, as already described, in excellent physical and mental condition.
I was aware that LSD, a new active compound with such properties, would have to be of use in pharmacology, in neurology, and especially in psychiatry, and that it would attract the interest of concerned specialists. But at that time I had no inkling that the new substance would also come to be used beyond medical science, as an inebriant in the drug scene. Since my self-experiment had revealed LSD in its terrifying, demonic aspect, the last thing I could have expected was that this substance could ever find application as anything approaching a pleasure drug.

Source: LSD : My Problem Child (1980), Ch. 1 : How LSD Originated
Context: This self-experiment showed that LSD-25 behaved as a psychoactive substance with extraordinary properties and potency. There was to my knowledge no other known substance that evoked such profound psychic effects in such extremely low doses, that caused such dramatic changes in human consciousness and our experience of the inner and outer world.
What seemed even more significant was that I could remember the experience of LSD inebriation in every detail. This could only mean that the conscious recording function was not interrupted, even in the climax of the LSD experience, despite the profound breakdown of the normal world view. For the entire duration of the experiment, I had even been aware of participating in an experiment, but despite this recognition of my condition, I could not, with every exertion of my will, shake off the LSD world. Everything was experienced as completely real, as alarming reality; alarming, because the picture of the other, familiar everyday reality was still fully preserved in the memory for comparison.
Another surprising aspect of LSD was its ability to produce such a far-reaching, powerful state of inebriation without leaving a hangover. Quite the contrary, on the day after the LSD experiment I felt myself to be, as already described, in excellent physical and mental condition.
I was aware that LSD, a new active compound with such properties, would have to be of use in pharmacology, in neurology, and especially in psychiatry, and that it would attract the interest of concerned specialists. But at that time I had no inkling that the new substance would also come to be used beyond medical science, as an inebriant in the drug scene. Since my self-experiment had revealed LSD in its terrifying, demonic aspect, the last thing I could have expected was that this substance could ever find application as anything approaching a pleasure drug.

Weapons of Self Destruction (2010)

Source: LSD : My Problem Child (1980), Ch. 11 : LSD Experience and Reality
Context: As a path to the perception of a deeper, comprehensive reality, in which the experiencing individual is also sheltered, meditation, in its different forms, occupies a prominent place today. The essential difference between meditation and prayer in the usual sense, which is based upon the duality of creator-creation, is that meditation aspires to the abolishment of the I-you-barrier by a fusing of object and subject, of sender and receiver, of objective reality and self.
Objective reality, the world view produced by the spirit of scientific inquiry, is the myth of our time. It has replaced the ecclesiastical-Christian and mythical-Apollonian world view.
But this ever broadening factual knowledge, which constitutes objective reality, need not be a desecration. On the contrary, if it only advances deep enough, it inevitably leads to the inexplicable, primal ground of the universe: the wonder, the mystery of the divine — in the microcosm of the atom, in the macrocosm of the spiral nebula; in the seeds of plants, in the body and soul of people.