For a good tree brings not forth corrupt fruit; neither does a corrupt tree bring forth good fruit.
All Commentaries on Luke 6:43 Go To Luke 6
Isodore of Seville
AD 636
He does not then exclude repentance, but a continuance in evil, which aslong as it is evil cannot bring forth good fruit, but being converted to virtue, will yield abundance. But what nature is to the tree, our affections are to us. If then a corrupt tree cannot bring forth good fruit, how shall a corrupt heart?