We can study various psychic functions and also the more primitive sensory functions, such as seeing, hearing, and so on, which constitute our image of our everyday world. They have a material side and the psychic side. And that is a gap which you cannot explain.
Albert HofmannWe can study material processes and various processes at the energetic level, that is what we can do as natural scientists. And then there comes something quite different, the psychic experience, which remains a mystery.
Albert Hofmann