Serenus: The authority of holy Scripture says on those points on which it would inform us some things so plainly and clearly even to those who are utterly void of understanding, that not only are they not veiled in the obscurity of any hidden meaning, but do not even require the help of any explanation, but carry their meaning and sense on the surface of the words and letters: but some things are so concealed and involved in mysteries as to offer us an immense field for skill and care in the discussion and explanation of them. And it is clear that God has so ordered it for many reasons: first for fear lest the holy mysteries, if they were covered by no veil of spiritual meaning, should be exposed equally to the knowledge and understanding of everybody, i.e., the profane as well as the faithful and thus there might be no difference in the matter of goodness and prudence between the lazy and the earnest: next that among those who are indeed of the household of faith, while immense differences of intellectual power open out before them, there might be the opportunity of reproving the slothfulness of the idle, and of proving the keenness and diligence of the earnest. And so holy Scripture is fitly compared to a rich and fertile field, which, while bearing and producing much which is good for man's food without being cooked by fire, produces some things which are found to be unsuitable for man's use or even harmful unless they have lost all the roughness of their raw condition by being tempered and softened down by the heat of fire. But some are naturally fit for use in both states, so that even when uncooked they are not unpleasant from their raw condition, but still are rendered more palatable by being cooked and heated by fire. Many more things too are produced only fit for the food of irrational creatures, and cattle, and wild animals and birds, but utterly useless as food for men, which while still in their rough state without being in any way touched by fire, conduce to the health and life of cattle. And we can clearly see that the same system holds good in that most fruitful garden of the Scriptures of the Spirit, in which some things shine forth clear and bright in their literal sense, in such a way that while they have no need of any higher interpretation, they furnish abundant food and nourishment in the simple sound of the words, to the hearers: as in this passage: "Hear, O Israel, the Lord thy God is one Lord;" and: "Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength." 
But there are some which, unless they are weakened down by an allegorical interpretation, and softened by the trial of the fire of the spirit cannot become wholesome food for the inner man without injury and loss to him; and damage rather than profit will accrue to him from receiving them: as with this passage: "But let your loins be girded up and your lights burning;" and: "whosoever has no sword, let him sell his coat and buy himself a sword;" and: "whosoever taketh not up his cross and followeth after Me is not worthy of Me;" 
a passage which some most earnest monks, having "indeed a zeal for God, but not according to knowledge" 
understood literally, and so made themselves wooden crosses, and carried them about constantly on their shoulders, and so were the cause not of edification but of ridicule on the part of all who saw them. But some are capable of being taken suitable and properly in both ways, i.e., the historical and allegorical, so that either explanation furnishes a healing draught to the soul; as this passage: "If any one shall smite thee on the right cheek, turn to him the other also;" and: "when they persecute you in one city, flee to another;" and: "if thou wilt be perfect, go, sell all that thou hast and give to the poor, and thou shalt have treasure in heaven, and come follow Me." 
It produces indeed "grass for the cattle" also, (and of this food all the fields of Scripture are full); viz., plain and simple narratives of history, by which simple folk, and those who are incapable of perfect and sound understanding (of whom it is said "Thou, Lord, wilt save both man and beast") 
may be made stronger and more vigorous for their hard work and the labour of actual life, in accordance with the state and measure of their capacity.