We tend to think of "fruit" in two ways in natural language. One is as food that grows on trees and vines, sweet and delicious, and able to be eaten without harming the plant in any way. Another is as the things we produce, what our work yields for the betterment of the world. These are obviously connected: we are like trees, producing things that "feed" the world in some way, just as the tree produces fruit that feeds us. It makes sense, then, that the idea of fruit in the Bible is bound closely to the idea of goodness. Fruits that are eaten represent the desire for good and the energy to do what is good; fruit that is produced is the actual good that we go into the world and do.

35. Man has two inherent powers of will and understanding. When the understanding is governed by the will they then constitute one mind and so one life; for what a person in that case wills and does he also thinks and intends. But when the understanding is at variance with the will, as it is with people who claim to have faith and yet live otherwise, then a mind previously one is split in two. One half seeks to transport itself into heaven, while the other inclines towards hell. And because the will is what accomplishes everything, the whole man would rush straight into hell unless the Lord took pity on him.