This is one about dreaming, but it can be incorporated into psychedelic thinking:
"The only way to experience a dream is to wake up immediately after it."
This is actually extremely mind boggling if you understand what it means. It shows you how the time continuum can get really distorted. When you dream, it's like watching a movie. There's a progressive plot. But when it's over, the memory of 'watching' the dream fades away, and usually also the memory of what you saw. Only if you wake up during the dream, you remain with the experience of having seen it. It really gives you a feeling of how a future event can change the past. I guess it's pretty much an ineffable experience, because you have to undergo it in order to wrap your mind around it.
The same goes for psychedelics. For me, the moment of entering the tunnel is the feeling of waking up to a much bigger reality. Past events in my life take on a new form and shape. And it's not just memories getting messed up, I feel as though my whole life takes on new meaning.
When you're sober, your experiences are broken down into frames of time. Every living moment is nothing more than the memory of the previous second gone by. It's like you are not really a part of your life, but rather an entity within a body, gazing back at slowly fading horizons.
That's where psychedelics make a difference. When you are on it, time has no meaning. You experience emotions as pure boiling vibes of eternal energy. Past memories suddenly float all around you, free from the chains of physical constraints. You can travel back to the time when you were a fetus in a womb, and you can go even further back. You wind the universe's clocks back to the big bang, and sit back gazing upon the orgy of pure matter and mass.
But alas, you suddenly find yourself back in this world, sitting on your bed, with the restraints of life weighing down on your head. People start nagging you with earthly matters, do this, do that. You are back to experiencing the world as chunks of time passing by. You feel like a gilded creature, surrounded by brick walls, with the watch towers of society carefully on the lookout for anyone who tries to make a run for it.
That is, until the next trip.
(Shit's a bit digressive, so excuse me)