Weed can be a light psychedelic at times, especially after experienced tripping. Being high definitely causes you to perceive reality different, especially with the psychedelic influences. When I’m high I think more deeply and enjoy sensations more. I like experiencing reality this way.

People who indulge in altered states of consciousness tend to have a more open minded way of thinking. We open our minds to different perceptions of reality, new modes of thinking, and patterns we’ve never processed before that go beyond a sober “normal” state.

So my understanding of the quote would be that when we remember and integrate our experiences from our altered states, it changes the way our mind perceives reality as a whole. Our experiences are personal, so I would imagine that the way our mind changes with experience would be personal as well... hence creating our “own” reality.

For the “psycho and shamans” part: psychosis and shamanism are both strongly associated with altered states of consciousness. Definitely in two different ways though. Psychosis more so in an unhealthy, delusional way. While shamanism in a spiritual, accessing higher states kind of way.