säuern

From LSJ

ὁ γὰρ μανθάνων κιθαρίζειν κιθαρίζων μανθάνει κιθαρίζειν → he who is learning the harp, learns the harp by harping

Source

German > Latin

säuern, das Brot, fermentare (d. i. gären machen). – gesäuertes Brot, panis fermentatus od. fermento imbutus.