In my opinion a trip is somehow like dying(someone who ever might have had a DMT trip will know what i'm talking about 8) ), a trip to heaven if you want to say so, that magical place where everything can happen (in reality it's more like a trip into your deeper self)
at that place there are no rules for to being alive as in our normal human society, that place where you become one with everything surrounding you, that place where, at least for some time, nothing matters anymore, not even you.
And, furthermore, you come into peace with yourself(if you are "authorised" to, not by the drug, but by yourself; if your live sucks, a trip will suck), and finally take some time to do things you always wanted to do on a trip.
I think that, most of the things that happen to you on a trip, happen to you because you wanted them to happen (or are forced to happen to you so you can go further on with your live; what a bad trip is like about, most of the people who had a bad trip say that, in the afterwards, for them as people, it has been an insight)
as someone mentioned here before, when he's on a trip he most of the time likes to talk and not think, it is because you want to share things with people you have discovered(or at least think you have discovered) which you normally couldn't tell if you were sober, because of you thinking them not to believe under that circumstances, but, at such a special moment in time and space, he HAS to belive you, or that's at least what you want to belive(or just because you want to want to enjoy the fun of talking/meeting people, and so on and son on(as i mentioned before, it depends on your will
)
let's be honest, thinking on psychedelic drugs is, let's say, too fast to really follow, a thought comes by, stays in your mind and is gone as fast as he has come, but there always will be some insights you had on a trip you can take to "the other side", the sober life(or at least non psychedelic one ^^)
to come back to this "oneness" thing, i really do belive in it.
In my opinion there is like only one consciousness, because we are all the same and all (somehow)want the same things, lead the life we want to lead.
I think that the soul, if you want to say so, is the same within what fullfills every living creature, that's why you can "communicate" whith every one, even with animals for example. The only thing that makes those lifes different is the fact that they are living their own life(and the shape of their physical manifestion)
to say it in short terms: on a trip you become one with what you are, the world that surrounds you. In return, when you are sober, you don't want to really be part of something, because of you wanting to live your own life, want to change you and the world around you(Evolution? ^^).
Reminds me of a quote i have once read "Every living cell on this planet is living on cost of the entropy of the universe"(because it organizes the atoms it is made of)