Otherwise; by the eye here we may understand our purpose; if that be pure and right, all our works which we work according thereto are good. These He here calls the body, as the Apostle speaks of certain works as members; “Mortify your members, fornication and uncleanness.” [Col 3:5]
We should look then, not to what a person does, but with what mind he does it. For this is the light within us, because by this we see that we do with good intention what we do. “For all which doth make manifest is light.” [Eph 5:13] But the deeds themselves, which go forth to men’s society, have a result to us uncertain, and therefore He calls them darkness; as when I give money to one in need, I know not what he will do with it.
If then the purport of your heart, which you can know, is defiled with the lust of temporal things, much more is the act itself, of which the issue is uncertain, defiled. For even though one should reap good of what you do with a purport not good, it will be imputed to you as you did it, not as it resulted to him. If however our works are done with a single purport, that is with the aim of charity, then are they pure and pleasing in God’s sight.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).