Gregory the Great — as excerpted in the Catena Aurea on Matthew 3:11-12

“(Mor. xxxiv. 5.) After the threshing is finished in this life, in which the grain now groans under the burden of the chaff, the fan of the last judgment shall so separate between them, that neither shall any chaff pass into the granary, nor shall the grain fall into the fire which consumes the chaff.”