Last week, I was reading comedian Lewis Black's memoir "Me of Little Faith". He shared a number of experiences he had while growing up in the 60's. Needless to say, there were the obligatory drug stories, many of which colored how he feels about the world to this day. One of the main things he felt while under the power of illicit substances was that we are all connected to everyone and everything (the monster "Avatar" proposes the same). Now I believe this to be the case, though I don't typically experience it directly.
Many people will write off the things they feel while on drugs because, well, because they were on drugs, but I'm of the mind that they are capable of opening us up to deeper truths which makes it strange that the government makes depressants like alcohol legal, but not less potentially destructive substances like marijuana. I've never tried the stuff myself, but I can certainly see the appeal.
Of course, there are other ways that one can feel this oneness, meditation in particular, but I'm so lazy that I'd rather do it laying down instead of sitting up which leads in most cases to drifting off to sleep as opposed to achieving ultimate spiritual creaminess. Black's not much different, stating that he'd rather masturbate than meditate, that both lead to the same conclusion, anyway.