4 Let each one then be a good tree; let him not suppose that he can bear good fruit, if he remain a corrupt tree. There will be no good fruit, but from the good tree. Change the heart, and the work will be changed. Root out desire, plant in charity. “For as desire is the root of all evil,” so is charity the root of all good. Why then do men fret and contend one with another, saying, “What is good?” O that you knew what good is! What you wish to have is not very good; this is good which you do not wish to be.
For you wish to have health of body; it is good indeed; yet you can not think that to be any great good, which the wicked have as well. Thou dost wish to have gold and silver; I grant that these also are good things, but then only if you make a good use of them; and a good use of them you will not make, if you are evil yourself. And hence gold and silver are to the evil evil; to the good are good, not because gold and silver make them good; but because they find them good, they are turned to a good use. Again, you wish to have honour, it is good; but this too only if you make a good use of it. To how many has honour been the occasion of destruction! And again, to how many has honour been the instrument of good works!
Source: Sermons on Selected Lessons of the New Testament (New Advent)