Paul, in Gal. v., points out the fruits which follow faith. The fruits of the Spirit, he says, are joy, peace, long-suffering, kindness, goodness, faith, meekness, temperance. So St. Peter speaks here of the fruit of faith,--to wit, that we should purify our souls, through obedience to the truth in the Spirit. For where there is real faith it brings the body in subjection to itself, and controls the fleshly lust; and although it does not entirely destroy it, yet it makes it subject and obedient to the Spirit, and holds it in check. St. Paul implies the same thing when he speaks of the fruits of the Spirit. It is a great achievement that the Spirit should attain control over the flesh, and restrain the evil lust which descends to us from our parents: for it is not possible that we should succeed without grace in leading a chaste life in the married state, to say nothing of the unmarried. But why does he say then, purify your souls? He is well aware that the desires of the flesh remain with us after baptism, even to the grave. Therefore it is not enough that a person should refrain from works and remain pure outwardly, while he permits evil lusts to cleave to his heart, but must thereafter beware that the soul be pure, as well as whatever proceeds out of the heart, and that the soul be opposed to these wicked lusts and desires, and continually contend therewith, until it is free from their power. And here he adjoins an excellent provision: that we should purify our souls,[3] _through obedience to the truth in the Spirit_. Much has been preached on chastity, and many books have been composed on the subject. They have said, we should fast for so long a time, we should not eat flesh, we should not drink wine, etc., that we may be free from temptation. These things may perhaps have aided somewhat to that end, but it has not been enough, it has not subdued lust. [Footnote 3: Make them chaste.] So St. Jerome writes of himself, that he had mortified his body to such an extent that he had become like a Moor; still it had been of no avail, and he had dreamed of being at Rome at a revelry among harlots. St. Bernard also subjected himself to such austerities, and so mortified his body that it became offensive, as I said above. They endured severe temptation, and purposed thus to subdue it by external methods. But since it is external, it is only an outward plaster, with no inward application. So that it does not suffice to subdue lust.