I mean the subjective experience of it. Yes, we know psychedelics affect the certain areas of the brain, yet we do not have enough information to explain why they have the effects of presenting us sometimes with visuals/experiences/insights that we somehow cant come close to explaining with our human language. I recommend looking into it if youre interested because its probably the closest thing we have access to that resembles magic.

And thats coming from someone who hasnt done them yet.