The reviewer is indulging in Pynchon-esque language here. Pynchon is hard to read, and people still debate the meaning of his books. You might enjoy them if you let go of expecting every sentence to make logical sense.
Pynchon is a lyricist and a madman, and he's damned good at being both. I wince when I read others trying to cop his style, even if momentarily. Troy Patterson is good, often really good, but he sounds fake here.
You left out "glinting rich and strange", which helps to make sense of "into our eternal souls".
Black pearls are rare with a somewhat subjective beauty, "unfathomable" can be interpreted literally in the analogy but also holds its normal meaning, and "any other diver" refers to any author but Pynchon.
Full fathom five thy father lies;
Of his bones are coral made;
Those are pearls that were his eyes;
Nothing of him that doth fade,
But doth suffer a sea-change
Into something rich and strange.
For this to work beautifully, we would fathom pearls when finding or collecting them. afaik only depths of water can be the literal object of the verb to fathom. It doesn't quite succeed, here. Which is likely why Pynchon is celebrated and the reviewer is reviewing him, rather than the reverse.
Like Yolesaber suggests, this is a gross mis-characterization. You need to read more and more widely. It's no longer 1935. And even then, at the height of modernism, a wide spectrum existed.
Edit: Obviously, reading literature is an entirely optional activity. I don't mean to suggest that you are obligated to do so. Only that to be familiar with the subjects that one makes claims about isn't such a horrible idea.
Except that the current vogue in modern literature is hyper-realist memoiristic writing which eschews the Moderist approach of purpled prose in favor of more intimate relations between characters without overbearing literary flourishes e.g. Jonathan Franzen