this is a long-belated reply (I have just been in India without my computer) to the very helpful post by Steve Farmer on 14th October 2018 concerning stimulants (such as ephedra), hallucinations and soma.

I am well aware that chronic, high-dose consumption of stimulants such as ephedra, cocaine and amphetamines may engender hallucinations and all kinds of strange experiences. (On hallucinations in general, I found 'Hallucinations' by Oliver Sacks quite useful.)

Hallucinations may arise, as Steve Farmer usefully observes, in anyone whose default mode network has been interrupted by any means, whether that be through drugs, self-flagellation or whatever. Robin Cahart-Harris et al. have for several years been publishing interesting results of the action of LSD and psilocybin on the DMN.

However, I believe that the core of the issue relating to soma/haoma is whether or not soma/haoma was/is capable of inducing an 'entheogenic' state. (We are of course in the area of tricky and contentious demarcation criteria here.) I am not talking about strange hallucinogenic experiences but an experience of what might be called 'divine transcendence'. Even high doses of LSD in optimal, controlled conditions only induce a transcendent experience in about 6% of subjects (see my book for references). Such transcendent experiences may also involve hallucinations, but these are secondary (and relatively insignificant) phenomena in the context of a properly transcendent experience. Experience of the 'cosmic', non-dual void or Godhead is the paramount and rarely obtained treasure.

This state may of course be obtained through a variety of means, but a particular class of tryptamine alkaloids appears to have a unique capacity for facilitating this rare state, namely LSD, psilocybin and DMT, which share a very similar molecular structure. These are the 'classic' tryptamines. They all bind to the 5HT 2A receptor site in the brain.

I don't believe that the Vedic kavis revered soma for its capacity to induce hallucinations, but because it could, occasionally, permit access to the divine light.

If we are looking for the divine entheogen, then I think we need to be looking for a tryptamine of one kind or another. Psilocybin mushrooms can, I believe, be confidently ruled out, for a variety of reasons. So, I believe we need to consider DMT + MAOIs and ayahuasca analogues as soma/haoma, most probably boosted in some instances (as in South America) by other plants, such as ephedra (or coca in South America).

Soon, Matthew Clark.