So, here's a quote I was looking for, as it turned out in the wrong place, which I thought I'd share.
Writing of the author of SIR GAWAIN & THE GREEN KNIGHT, Tolkien says
Of this author, nothing is now known.* But he was a major poet of his day; and it is a solemn thought that his name is now forgotten, a reminder of the great gaps of ignorance over which we now weave the thick webs of our literary history. But something to the purpose may still be learned of this writer from his works.
I thought this came from the Tolkien/Gordon edition of SGGK (1925).
Turns out it appears in JRRT's SGGK translation (1975), Introduction p.13.
*except that he probably wrote three other works: PEARL, PATIENCE, and PURITY.
Of these three, I strongly recommend PATIENCE, a hilarious retelling of the Jonah story.