“The brain is the medium of expression of the human mind. Similarly the entire physical universe would be the medium of expression of the mind of a natural God.”

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.

George Boole, quoted in Kenneth E. Iverson's 1979 Turing Award Lecture
Attributed from posthumous publications

Internet Encyclopedia of Philosophy

'Painting and Culture' p. 55
Search for the Real and Other Essays (1948)

'Search for the Real in the Visual Arts', p. 46
Search for the Real and Other Essays (1948)

'Painting and Culture' p. 58
Search for the Real and Other Essays (1948)

As quoted in Man Ray : The Rigour of Imagination (1977) by Arturo Schwarz, p. 10 <!-- also in Man Ray : Photographs and Objects (1980) by Birmingham Museum of Art -->
Variant: I paint what cannot be photographed, that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence.
As quoted in an interview "Man Ray: Photographer" published in Camera (1981) edited by Philippe Sers <!-- and in The Columbia Dictionary of Quotations (1993) edited by Robert Andrews, p. 686 -->
Context: l paint what cannot be photographed, and l photograph what l do not wish to paint. lf it is a portrait that interests me, a face, or a nude, I will use my camera. It is quicker than making a drawing or a painting. But if it is something I cannot photograph, like a dream or a subconscious impulse I have to resort to drawing or painting. To express what I feel I use the medium best suited to express that idea, which is also always the most economical one. l am not at all interested in being consistent as a painter, and object-maker or a photographer. I can use several different techniques, like the old masters who were engineers, musicians and poets at the same time. I have never shared the contempt shown by painters for photography: there is no competition involved, painting and photography are two media engaged in different paths. There is no conflict between the two.

'Painting and Culture' p. 58
Search for the Real and Other Essays (1948)

'Excerpts from the Teaching of Hans Hofmann', p. 61
Search for the Real and Other Essays (1948)