I haven’t read the book, but it sounds like a good one.
On the other hand, while I started to watch the McKenna video, I had to stop part way in. Of course we may never fully understand the universe. It may itself be fractal, with no limit to its complexity. Matter is made of molecules made of atoms made of bosons made of quarks made of . . . . who knows? But just because we may never understand the totality of reality, we can still understand parts of it. To say that our role is not to understand but to appreciate* is to limit ourselves to staring wondrously at the universe with jaws hanging slack. Poo on that. I’d rather try to understand as much as I can. Within that understanding, however limited, comes incredible beauty. Now if that was McKenna’s point, then I apologize, but he sure had a weird way of approaching the matter.
*I assume he’s using “appreciate” to mean enjoy rather than understand, otherwise the sentence wouldn’t make sense.