14. But in addition to the foregoing rule, which guards us against taking a metaphorical form of speech as if it were literal, we must also pay heed to that which tells us not to take a literal form of speech as if it were figurative. In the first place, then, we must show the way to find out whether a phrase is literal or figurative. And the way is certainly as follows: Whatever there is in the word of God that cannot, when taken literally, be referred either to purity of life or soundness of doctrine, you may set down as figurative. Purity of life has reference to the love of God p. 561 and ones neighbor; soundness of doctrine to the knowledge of God and ones neighbor. Every man, moreover, has hope in his own conscience, so far as he perceives that he has attained to the love and knowledge of God and his neighbor. Now all these matters have been spoken of in the first book.
15. But as men are prone to estimate sins, not by reference to their inherent sinfulness, but rather by reference to their own customs, it frequently happens that a man will think nothing blameable except what the men of his own country and time are accustomed to condemn, and nothing worthy of praise or approval except what is sanctioned by the custom of his companions; and thus it comes to pass, that if Scripture either enjoins what is opposed to the customs of the hearers, or condemns what is not so opposed, and if at the same time the authority of the word has a hold upon their minds, they think that the expression is figurative. Now Scripture enjoins nothing except charity, and condemns nothing except lust, and in that way fashions the lives of men. In the same way, if an erroneous opinion has taken possession of the mind, men think that whatever Scripture asserts contrary to this must be figurative. Now Scripture asserts nothing but the catholic faith, in regard to things past, future, and present. It is a narrative of the past, a prophecy of the future, and a description of the present. But all these tend to nourish and strengthen charity, and to overcome and root out lust.
16. I mean by charity that affection of the mind which aims at the enjoyment of God for His own sake, and the enjoyment of ones self and ones neighbor in subordination to God; by lust I mean that affection of the mind which aims at enjoying ones self and ones neighbor, and other corporeal things, without reference to God. Again, what lust, when unsubdued, does towards corrupting ones own soul and body, is called vice; 1859 but what it does to injure another is called crime. 1860 And these are the two classes into which all sins may be divided. But the vices come first; for when these have exhausted the soul, and reduced it to a kind of poverty, it easily slides into crimes, in order to remove hindrances to, or to find assistance in, its vices. In the same way, what charity does with a view to ones own advantage is prudence; but what it does with a view to a neighbors advantage is called benevolence. And here prudence comes first; because no one can confer an advantage on another which he does not himself possess. Now in proportion as the dominion of lust is pulled down, in the same proportion is that of charity built up.