Winnowing.
This was accomplished in the open air, by throwing up the grain with a shovel, or a fan (liknos, really a kind of shallow basket); the wind carried away the chaff. Boaz winnowed his barley in the evening, when there would be more wind. Ruth 3:2; Isaiah 30:24. John the Baptist said of the Lord that His fan was in His hand, and He would thoroughly purge His floor; gather His wheat into the garner; and burn up the chaff with unquenchable fire. Matthew 3:12; Luke 3:17. It is now a day of grace, a sowing time, but the harvest will come, and the winnowing will surely follow.