“Every one of us has a sense of the world, and we all know that this sense is in part given to us by what other people and society tell us; in part generated by our emotional state, which we project outward; and in part by our genuine perceptions of reality. In short, our struggle to determine what is true is the struggle to decide which of our perceptions is genuine, and which are false because they are handed down, or sold to us, or generated by our own hopes and fears.”

Essay as "Mr. X" (1969)
Context: I can remember the night that I suddenly realized what it was like to be crazy, or nights when my feelings and perceptions were of a religious nature. I had a very accurate sense that these feelings and perceptions, written down casually, would not stand the usual critical scrutiny that is my stock in trade as a scientist. If I find in the morning a message from myself the night before informing me that there is a world around us which we barely sense, or that we can become one with the universe, or even that certain politicians are desperately frightened men, I may tend to disbelieve; but when I'm high I know about this disbelief. And so I have a tape in which I exhort myself to take such remarks seriously. I say "Listen closely, you sonofabitch of the morning! This stuff is real!" I try to show that my mind is working clearly; I recall the name of a high school acquaintance I have not thought of in thirty years; I describe the color, typography, and format of a book in another room and these memories do pass critical scrutiny in the morning. I am convinced that there are genuine and valid levels of perception available with cannabis (and probably with other drugs) which are, through the defects of our society and our educational system, unavailable to us without such drugs. Such a remark applies not only to self-awareness and to intellectual pursuits, but also to perceptions of real people, a vastly enhanced sensitivity to facial expression, intonations, and choice of words which sometimes yields a rapport so close it's as if two people are reading each other's minds.

Source: Marihuana Reconsidered

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Books, Reflections on Sacred Teachings, Volume IV: Sri Isopanisad (Hari-Nama Press, )

Source: Reason: The Only Oracle Of Man (1784), Ch. V Section II - Containing Observations on the Providence and Agency of God, as it Respects the Natural and Moral World, with Strictures on Revelation in General
Context: There has in the different parts and ages of the world, been a multiplicity of immediate and wonderful discoveries, said to have been made to godly men of old by the special illumination or supernatural inspiration of God, every of which have, in doctrine, precept and instruction, been essentially different from each other, which are consequently as repugnant to truth, as the diversity of the influence of the spirit on the multiplicity of sectaries has been represented to be.
These facts, together with the premises and inferences as already deduced, are too evident to be denied, and operate conclusively against immediate or supernatural revelation in general; nor will such revelation hold good in theory any more than in practice. Was a revelation to be made known to us, it must be accommodated to our external senses, and also to our reason, so that we could come at the perception and understanding of it, the same as we do to that of things in general. We must perceive by our senses, before we can reflect with the mind. Our sensorium is that essential medium between the divine and human mind, through which God reveals to man the knowledge of nature, and is our only door of correspondence with God or with man.

1960s, (1969)

Solaris (1961), Ch. 6: "The Little Apocrypha", p. 72
Solaris (1961)

On My Philosopy (1941)

Source: Pre-1960, Profiles in Courage (1956), p. 15