The threshing floor is your inner life, and the one holding the winnowing fork is the whole, true self, the drive toward wholeness that ruthlessly separates what lasts from what has to burn.
Long before this image, the winnowing basket already carried old meanings of initiation and rebirth. The fire that burns the chaff is not punishment but a holy fire that cannot be put out, the same cleansing heat that old thinkers said burns every trace of blackness out of raw material. Real growth asks for exactly this burning: not the hoarding of every scrap the proud self collects, but the destroying of your coarser, rejected leftovers, so that only the lasting wheat remains, the true core of who you really are.