Let a vet throw a mataphor milkbone to all you starving psychedelipuppies!
In routine conscious awareness, you are standing directly front and center before the door of perception.
When you ingest a mind-altering substance, idea or experience, you shift a little to one side and/or up or down. You now can see less that you could before, but you can see some things you couldn't see before (although more which you could see before is now hidden or overwhelmed). So it's a bad deal. Right? Wrong! (because humans have this little thing called memory, which allows them to summate perspectives, ideas and experiences). So any altered view may show you less, but it's an "in addition to" rather than an "instead of". Therefore the sum of the shaman is always greater, because it includes that lagniappe, the "extra" not ordinarily susceptible to view, while still retaining all the standard perceptions, cognitions and attitudes.
Joe E. Dees
Poet, Pagan, Philosopher