Moses was tripping when he saw the burning bush and received the Ten Commandments, according to Benny Shanon, a professor of cognitive psychology at the Hebrew University of Jerusalem. (Source: Haaretz)
According to Shanon, the patriarch was high on a concoction "based on bark of the acacia tree, that is frequently mentioned in the Bible." There are over a thousand different species of acacia found in southern Asia, Africa and the Americas, and many of them contain psychotropic alkaloids like DMT, a powerful hallucinogen which also occurs naturally in the human brain.
The theory that Moses was under the influence of a psychedelic plant when he spoke to Yahweh isn't all that outlandish. The idea that religions originated with the ritual use of entheogenic plants--psychoactive plants used in religious or shamanic contexts--is nothing new and has been clearly demonstrated in other cultures. For instance, the use of peyote, psilocybin mushrooms and other hallucinogenic plants like datura (jimson weed) was widespread in the early Americas. The soma described in the Rig Vedas was a drink prepared from a plant which has been variously described as a psychedelic mushroom or the Nile water lily, also known as the blue water lotus, recently discovered to have psychotropic properties. In "The Sacred Mushroom and The Cross," the Dead Sea Scrolls scholar Dr. John Allegro argues that Christianity originated in Near East fertility cults centered around the ritual use of Amanita Muscaria, a psychedelic mushroom also known as fly agaric or fly Amanita.
So none of this is new. The only problem with Shanon's theory is that there's no evidence that Moses ever existed in the first place, so the question of whether he was using acacia or not seems academic. See "The Bible Unearthed: Archeology's New Vision of Ancient Israel and the Origin of Its Sacred Texts," by Finkelstein and Silberman for details. In fact, it could be argued that the only people who are hallucinating are those who believe that legendary characters like Moses were actual flesh-and-blood people who talked to God on mountaintops and could part the Red Sea on command. Maybe the fact that the hallucinogen DMT occurs naturally in the human brain has something to do with these widespread beliefs.