The Botany of Desire, by Michael Pollan
Chapter Title "Marijuana", Excerpts from pages 162 and 163:
The THC in marijuana and the brain's endogenous cannabinoids work in much the same way, but THC is far stronger and more persistent than anandamide, which, like most neurotransmitters, is designed to break down very soon after its release. (Chocoloate, of all things, seems to slow this process, which might acocunt for its own subtle mood-altering properties.) What this suggests is that smoking marijuana may overstimulate the brain's built-in forgetting faculty, exaggerating its normal operations.
This is no small thing. Indeed, I would venture that, more than any other single quality, it is the relentless moment-by-moment forgetting, this draining of the pool of sense impression almost as quickly as it fills, that give the experience of consciousness under marijuana its peculiar texture. It helps account for the sharpening of sensory perceptions, for the aura of profundity in which cannabis bathes the most ordinary insights, and, perhaps most important of all, for the sense that time has slowed or even stopped. For it is only by forgetting that we ever really drop the thread of time and approach the experience of living in the present moment, so elusive in ordinary hours. And the wonder of that experience, perhaps more than any other, seems to be at the very heart of the human desire to change consciousness, whether by means of drugs or any other technique.
"Consider the cattle, grazing as they pass you by," Friedrich Nietzsche begins a brilliant, somewaht eccentric 1876 essay he called "The Uses and Disadvantages of History for Life." "They do not know what is meant by yesterday or today, they leap about, eat, rest, digest, leap about again, and so from morn till night and from day to day, fettered to the moment and its pleasure or displeasure, and thus neither melancholy nor bored....
"A human being may well ask an animal: 'Why do you not speak to me of your happiness but only stand and gaze at me?" The animal would like to answer, and say, 'The reason is I always forget what I was going to say'--- but then he forgot this answer too, and stayed silent."
The first part of Nietzche's essay is a moving and occasionally hirarious paean to the virtues of forgetting, which he maintains is a prerequisite to human happiness, mental health, and action. Without dismissing the value of memory or history, he argues (much like Emerson and Thoreau) that we spend altogether too much of our energy laboring in the shadows of the past-- under the stultifying weight of convention, precedent, received wisdom, and neurosis. Like the American transcendentalists, Nietzsche believes that our personal and collective inhertiance stands in the way of our enjoyment of life and accomplishment of anything original.