Catena Aurea on John 15:12–16: Gregory the Great

I have set you,i. e. have planted you by grace, that ye should go by will (volendo not in Vulg.); to will being to go in mind, and bring forth fruit, by works. What kind of fruit they should bring forth He then shews: And that your fruit may remain: for worldly labour hardly produces fruit to last our life: and if it does, death comes at last, and deprives us of it all. But the fruit of our spiritual labours endures even after death; and begins to be seen at the very time that the results of our carnal labour begin to disappear. Let us then produce such fruits as may remain, and of which death, which destroys every thing, will be the commencement.