The last paragraph:
LSD is a much "dirtier drug" than psilocybin. Psilocybin acts specifically on serotonin receptors in the brain and perhaps also on glutamate receptors. LSD acts on all kinds of receptors in a much wilder fashion. Because of this difference, people exposed to psilocybin don’t lose a sense of being the agents of their illusions and hallucinations. They don’t enter a fully psychotic state with head voices and paranoia, as can be the case with LSD. People exposed to psilocybin sometimes report a liberating loss of time and space and personal identity through space and time. “It’s usually not a loss of the physical body,” says MacLean, “it’s the loss of the sense of ‘I am Katherine, sitting at my desk in this year 2012 and I had a childhood and then I went to college and then I moved across the country a couple of times and in the future I would like to do these things.’ That whole narrative is lost. You are an observer experiencing something but you are not a human being who has a certain identity. You are pure agency capable of experiencing the true nature of the universe.”