Personally, the last (and admittedly only) time I tripped on mushrooms it was the most genuinely spiritual experience of my life, and that's coming from the son of a Dawkins-level athiest mother.
At the end of it, I just felt more content with my place in the universe. The feeling eventually faded, but the idea that a treatment for depression could be effective for months on a single dose (or permanently) is definitely worth investigating. Certainly better than SSRIs that have to be taken daily for weeks before seeing results, and ultimately result in uncomfortable withdrawals if you stop. The western world needs to sort itself out with regard to legal and illegal drugs, thats for sure.