A complicated sentence occurring in Tolkien's "Silmarillion"

I’ve come across a rather complicated sentence in Tolkien’s work "The Silmarillion" and I’m afraid that I need some help at understanding its meaning, and therefore its grammar. It reads as thus:

From without the world, though all things may be forethought in music or foreshown in visions from afar, to those who enter verily into Eä each in its time shall be met at unawares as something new and unforetold.

Let me explicate my attempts at deciphering this sentence. First, I believe that the first comma is not a true separation, so that the first part of the sentence may be understood as "Though all things may be forethought […] from without the world,". Then "unawares" is not a noun, so that the "at" that comes right before it must refer to something else, and the only choice would be "each", so that "those who enter" meet at "each". (On the other hand, if "unawares" was indeed somehow something at which one could meet, then one might conjecture the sentence to mean that "those who enter" somehow meet "each" unexpectedly, or something like that. But then I’ve never come across the construction "to meet sth. to so.", which seems to have been used here. I then have to assume it to mean something like "make so. acquainted with sth.")

An alternate interpretation of the "to those" might be that it stands in conjunction with the "From" in the beginning of the sentence, indicating that from any perspective, "each in its time" will be "met at" unawares.

Which of these thoughts are correct? What is the sentence’s true meaning? I’d greatly appreciate any help!