In the Amazon and other places where visionary plants are understood and used, you are conveyed into worlds that are appallingly different from ordinary reality. Their vividness cannot be stressed enough. They are more real than real, and that's something that you sense intuitively. They establish an ontological priority. They are more real than real, and once you get that under your belt and let it rattle around in your mind, then the compass of your life begins to spin and you realize that you are not looking in on the Other; the Other is looking in on you. This is a tremendous challenge to the intellectual structures that have carried us so far during the last thousand years. We can do tricks with atoms, there's no question about that, but these tricks immolate us. The higher-order structure of molecules, let alone organelles and that kind of thing, is intellectual incognita to us. We have no notion of how these things work or what is going on. Yet it is from those levels that the constituent modalities of reality are being laid down.

Terence McKenna [1946-2000]