Mythopoeia (Greek, "mythos-making") is the title of a poem by J.R.R. Tolkien, and the name of a term coined by him.
"Mythopoeia" was created as reaction to C.S. Lewis' statement that myths were "lies breathed through silver." The poem takes a position opposed to rationalism and materialism, referring to the creative human author as "the little maker" wielding his "own small golden sceptre" ruling his Subcreation (understood as genuine Creation within God's primary Creation).
While quoted in "On Fairy-Stories" (1947), and mentioned by Humphrey Carpenter in his J.R.R. Tolkien: A Biography (1977), the poem was first published in its entirety in the 1988 edition of Tree and Leaf.
I will not treat your dusty path and flat,
denoting this and that by this and that,
your world immutable wherein no part
the little maker has with maker's art.
I bow not yet before the Iron Crown,
nor cast my own small golden sceptre down.