Isaias 7:9

But the husbandry is twofold, the one unwritten, and the other written. And in whatever way the Lord’s labourer sow the good wheat, and grow and reap the ears, he shall appear a truly divine husbandman. “Labour,” says the Lord, “not for the meat which perisheth, but for that which endureth to everlasting life.” And nutriment is received both by bread and by words. And truly “blessed are the peace-makers,” who instructing those who are at war in their life and errors here, lead them back to the peace which is in the Word, and nourish for the life which is according to God, by the distribution of the bread, those “that hunger after righteousness.” For each soul has its own proper nutriment; some growing by knowledge and science, and others feeding on the Hellenic philosophy, the whole of which, like nuts, is not eatable. …

It is clear, then, that the truth has been hidden from us; and if that has been already shown by one example, we shall establish it a little after by several more. How entirely worthy of approbation are they who are both willing to learn, and able, according to Solomon, “to know wisdom and instruction, and to perceive the words of wisdom, to receive knotty words, and to perceive true righteousness,” there being another [righteousness as well], not according to the truth, taught by the Greek laws, and by the rest of the philosophers. …

says Homer. “But each has his own proper gift of God”, one in one way, another in another. But the apostles were perfected in all. You will find, then, if you choose, in their acts and writings, knowledge, life, preaching, righteousness, purity, prophecy. We must know, then, that if Paul is young in respect to time, having flourished immediately after the Lord’s ascension, yet his writings depend on the Old Testament, breathing and speaking of them. For faith in Christ and the knowledge of the Gospel are the explanation and fulfilment of the law; and therefore it was said to the Hebrews, “If ye believe not, neither shall you understand;” that is, unless you believe what is prophesied in the law, and oracularly delivered by the law, you will not understand the Old Testament, which He by His coming expounded.

But “what manner of man is this? for He commandeth even the winds and water!” Of course He is the new master and proprietor of the elements, now that the Creator is deposed, and excluded from their possession! Nothing of the kind. But the elements own their own Maker, just as they had been accustomed to obey His servants also. Examine well the Exodus, Marcion; look at the rod of Moses, as it waves His command to the Red Sea, ampler than all the lakes of Judæa. …

Who shall be invoked as the Lord of heaven, that does not first show Himself to have been the maker thereof? For He says, “I thank thee, (O Father) and own Thee, Lord of heaven, because those things which had been hidden from the wise and prudent, Thou has revealed unto babes.” What things are these? And whose? And by whom hidden? And by whom revealed? If it was by Marcion’s god that they were hidden and revealed, it was an extremely iniquitous proceeding; for nothing at all had he ever produced in which anything could have been hidden, no prophecies, no parables, no visions, no evidences of things, or words, or names, obscured by allegories and figures, or cloudy enigmas, but he had concealed the greatness even of himself, which he was with all his might revealing by his Christ. …

In Isaiah: “And if ye will not believe, neither will ye understand.” Also the Lord in the Gospel: “For if ye believe not that I am He, ye shall die in your sins.” Moreover, that righteousness should subsist by faith, and that in it was life, was predicted in Habakkuk: “Now the just shall live by faith of me.” Hence Abraham, the father of the nations, believed; in Genesis: “Abraham believed in God, and it was counted unto him for righteousness.” In like manner, Paul to the Galatians: “Abraham believed in God, and it was counted unto him for righteousness. Ye know, therefore, that they which are of faith, the same are children of Abraham. But the Scripture, foreseeing that God justifieth the heathens by faith, foretold to Abraham that all nations should be blessed in him. Therefore they who are of faith are blessed with faithful Abraham.”

In Genesis: “And Abraham believed God, and it was counted unto him for righteousness.” Also in Isaiah: “And if ye do not believe, neither shall ye understand.” Also in the Gospel according to Matthew: “O thou of little faith, wherefore didst thou doubt?” Also in the same place: “If you have faith as a grain of mustard seed, ye shall say to this mountain, Pass over from here to that place, and it shall pass over; and nothing shall be impossible unto you.” Also according to Mark: “All things whatsoever ye pray and ask for, believe that ye shall receive them, and they shall be yours.” Also in the same place: “All things are possible to him that believeth.” In Habakkuk: “But the righteous liveth by my faith.” Also in Daniel: “Ananias, Azarias, and Misael, trusting in God, were delivered from the fiery flame.”

Augustin, the man with upturned eye, with pen in the left hand, and a burning heart in the right (as he is usually represented), is a philosophical and theological genius of the first order, towering like a pyramid above his age, and looking down commandingly upon succeeding centuries. He had a mind uncommonly fertile and deep, bold and soaring; and with it, what is better, a heart full of Christian love and humility. He stands of right by the side of the greatest philosophers of antiquity and of modern times. We meet him alike on the broad highways and the narrow footpaths, on the giddy Alpine heights and in the awful depths of speculation, wherever philosophical thinkers before him or after him have trod. As a theologian he is facile princeps , at least surpassed by no church father, schoolman, or reformer. …

12. And until he be purged from this uncleanness, let him believe in the Father, Son, and Holy Spirit, one God, alone, great, omnipotent, good, just, merciful, Creator of all things visible and invisible, and whatsoever can be worthily and truly said of Him in proportion to human capacity. And when he is told that the Father only is God, let him not separate from Him the Son or the Holy Spirit; for together with Him He is the only God, together with whom also He is one God; because, when we are told that the Son also is the only God, we must needs take it without any separation of the Father or the Holy Spirit. And let him so say one essence, as not to think one to be either greater or better than, or in any respect differing from, another. …

2. For God Himself, whom we seek, will, as I hope, help our labors, that they may not be unfruitful, and that we may understand how it is said in the holy Psalm, “Let the heart of them rejoice that seek the Lord. Seek the Lord, and be strengthened: seek His face evermore.” For that which is always being sought seems as though it were never found; and how then will the heart of them that seek rejoice, and not rather be made sad, if they cannot find what they seek? For it is not said, The heart shall rejoice of them that find, but of them that seek, the Lord. …

These things you do not understand, because, as the prophet said, "Unless you believe, you shall not understand." For you are not instructed in the kingdom of heaven, that is, in the true Catholic Church of Christ. If you were, you would bring forth from the treasure of the sacred Scriptures things old as well as new. For the Lord Himself says, "Therefore every scribe instructed in the kingdom of heaven is like an householder who brings forth from his treasure things new and old." And so, while you profess to receive only the new promises of God, you have retained the oldness of the flesh, adding only the novelty of error; of which novelty the apostle says, "Shun profane novelties of words, for they increase unto more ungodliness, and their speech eats like a cancer. …

46. According to the teaching of the Catholic Church, the Christian mind must first be nourished in simple faith, in order that it may become capable of understanding things heavenly and eternal. Thus it is said by the prophet: "Unless ye believe, ye shall not understand." Simple faith is that by which, before we attain to the height of the knowledge of the love of Christ, that we may be filled with all the fullness of God, we believe that not without reason was the dispensation of Christ’s humiliation, in which He was born and suffered as man, foretold so long before by the prophets through a prophetic race, a prophetic people, a prophetic kingdom. This faith teaches us, that in the foolishness which is wiser than men, and in the weakness which is stronger than men, is contained the hidden means of our justification and glorification. …