I answer that, The principles of sinning are the same in us as the principles of action, for a sin is an act. Now there are in us three principles of action; the first is the directing principle, namely, the cognitive power; the second is the commanding principle, namely, the appetitive power; the third is the executive principle, namely, the motive power.
Now all our knowledge has its origin in the senses. And, since the remedy for sin should be applied where sin originates in us first, for that reason the places of the five senses are anointed. the eyes, to wit, on account of the sight, the ears on account of hearing, the nostrils on account of the smell, the mouth on account of the taste, the hands on account of the touch which is keenest in the finger tips, (in some places too the loins are anointed on account of the appetite), and the feet are anointed on account of the motive power of which they are the chief instrument. And since the cognitive power is the first principle of human activity, the anointing of the five senses is observed by all, as being essential to the sacrament. But some do not observe the other unctions---some also anoint the feet but not the loins---because the appetitive and motive powers are secondary principles.
