In every kind of doctrine, there exists only one path to its true and firm understanding and to acquiring a reliable judgment about its inherent matters: to have, according to a correct methodological procedure of teaching, the general principles outlined, which encompass the essence of the entire doctrine. For in no other way can one form in the mind a concept of the essence of any particular science. When we regard it thus, we more rightly comprehend the beginnings, the progression, and the heights of the doctrine. If thoughts are enclosed within these, so to speak, domains and firm dwellings, they do not wander aimlessly hither and thither like people who lack a fixed abode and have nowhere to pause or to proceed safely and securely.

On the basis of such principles, indeed, one can make judgments about any matter that falls within the realm of the doctrine. And finally, through them, we can, with less effort, impart very beneficial instruction to others. For particulars become clear when they are properly adapted to the corresponding general principles and when precepts are learnedly compared with examples.

However, in no kind of doctrine is the knowledge of general principles more necessary than in that which was given by divine agency concerning those mysteries that no sages could investigate without special divine revelation. For the more difficult these matters are, the more necessary is this study, which brings people to their firm understanding. So that they not only grasp the doctrine but may also, if need be, defend it against human as well as diabolical slander. Without this certainty and steadfastness, it is by no means possible to retain the treasure of eternal life, which is hidden exclusively in this doctrine.

The doctrine is, of course, expounded in that form even in those first beginnings that are presented to the youngest age of youth when they are taught about the Law, about the Gospel, and about the duties of those who have been reborn through the Gospel. Yet it is necessary to add to that form a certain more perfect one, for which those aforementioned first beginnings actually serve; for their aim is that this more perfect form may be acquired as easily as possible. For in every doctrine, such elementary instruction is first necessary, by which the unlearned and more rustic people of simple understanding are prepared for a better and easier reception of less known things—so to speak, the mysteries of the doctrine.

If to these two kinds of study is added the compilation of examples and direct proficiency in them, then nothing can be lacking to the true doctrine. For everyone who will be thus equipped will judge readily and wisely about the individual passages of Scripture; he will connect related and similar things, distinguish different ones. And finally, he will be prepared to resist adversaries headed by the devil. To overcome him, we need in doctrine presence of mind, certainty, and good preparation. According to Paul's desire, the bishop in the church, who is the overseer of doctrine, should be, above all, a teacher; that is, he himself should not only preserve the doctrine but also know how to expound it clearly and properly so that it can be understood. For the Church is not offended only by those who teach falsehoods but also by those who, though they teach true principles, do not respect the order of teaching and the requirement of clarity.

However, before we come to the proper doctrine of the Church of God, we must carefully distinguish the difference that appears between the precepts of other arts and true theology. For the devil always introduces great errors into the Church, partly through those who confuse the types of doctrines, partly through uneducated people who openly proclaim that noble learning not only does not benefit the teaching of the Church at all but even causes it the greatest harm, asserting that ignorance is wholesome and beneficial to piety. Such an opinion is now held by the Anabaptists and other unlearned individuals, who devise a truly dreadful and barbarous theology, and it is impossible to instruct or correct them, since they hold this main principle: that one must not believe scholars and truly learned people who expound doctrine properly and precisely. This barbarism pleases the masses, who ultimately hate doctrine, and it prepares the way for the complete destruction of all divine and human things from the memory of people.

When we wish to avoid both errors—one originating from the learned, the other from the unlearned—we must adhere to the correct distinction of doctrines. And above all, against the unlearned, we must recognize that for proper and orderly teaching in the Church and in schools, the knowledge of other arts is indispensable. It is necessary for preaching to resonate appropriately and clearly; therefore, we must learn to define or divide concepts and to form judgments from them. It is also required to possess extraordinary eloquence to extol worthy matters, to inspire, admonish, and encourage youth and the people in every way. For all this to be properly accomplished, one must acquire these skills, but without the disciplines of rhetoric, no one can succeed in this. For teachers, the knowledge of matters that constitute the content of the rest of philosophy is also indispensable. A knowledge of historical examples is also required so that the doctrine of the Church being discussed can be wisely illustrated. Even if one were to speak—setting aside other examples—only about the creation of things, even then it would be necessary to investigate the whole of nature as described by natural science authors.

But the unlearned object that for piety we need nothing other than what is contained in the books of Moses, the prophets, and the apostles. They claim that the books of Moses and other witnesses of God do not include the disciplines of rhetoric and matters related partly to the understanding of nature, partly to the understanding of the honorableness of deeds. Therefore, they assert that these subjects are not at all necessary for piety.

Before I begin to answer this argument, by which these people defend not Christian piety but their own ignorance, I will briefly mention the true validity of those manifestations found in the prophetic books. For God did not leave us that wisdom originating from Himself to detract in any way from the dignity of those arts that were already known to people of their own accord. They were created together with man as special gifts, made for humanity and entrusted to them to serve God, not the devil, and that much more than any other gifts a person can receive. Precisely through the knowledge of these arts, humanity had the highest possibility to express itself and glorify God—through the ability to speak, through the investigation of numbers, measures, customs, celestial motions, through the knowledge of other works, and especially through a clarified understanding of which deeds are honorable and pleasing to God alone. These have such power that if the devil had not led humanity astray, nothing else would have been necessary for living rightly before God's face, and it would have been required only to fulfill the duties for which God created humans, the creatures dearest to Him among all His creations. For humans would have truly understood both themselves and other works of God, and if they had diligently investigated and compared them, they would have genuinely acknowledged and glorified God as the Creator.

And now I will answer the main premise of their argument, which is evidently both erroneous and impious. Although the knowledge of worldly arts is not the reason we are in God's grace and heirs of eternal life (for even apostolic gifts are not sufficient for that!), it is nonetheless a mistake to say that this knowledge is not useful and necessary for piety and for the teaching of the Christian religion. For if it was beneficial in life uncorrupted by sin, how much more does it benefit now? Is there anything more impious, more barbarous than to call sins those arts which God Himself established and which are a special adornment of humanity among all that was granted at creation?

For all else man shares with the animals, whose bodily strengths and activity of external senses even surpass human abilities. But the knowledge of those arts, which are taught in schools with honest intention, is proper to humans and therefore necessary for the fulfillment of their other duties, as well as for that greatest service of all—through which the doctrine about God and divine matters is to become known—so that people truly understand it, accept it, and practice it with genuine effort, and so that it may spread to all future generations. In this matter, humans are companions of the angels, who stand before the sight of God and devote their time exclusively to glorifying Him. For such a great task, they are equipped solely with the ability to speak and sing about the works of God; to enumerate them and, according to their greatness, assess their importance. They are righteous, holy, pure, virtuous, and so forth.

Nor is the subsidiary premise of the argument more true and pious, for although the doctrine of the Church does not contain the precepts of other arts, yet agreement with them and excellent examples for this doctrine exist. Thus, God calls Aaron to Moses for his greater eloquence. And neither for prophetic and apostolic service does He choose people inexperienced in speech. So also the apostles, who held the highest office in the Church, He equipped not only with excellent understanding of the mysteries in Moses and the prophets but also with such knowledge of languages that they could speak well and appropriately in any language. And just as the Gospel does not propose laws for the arrangement of states—yet approves them if they are lawful—so it does not present the precepts of other arts, since that is not at all necessary, but certainly recommends them as special gifts of God.

Therefore, not only erroneous but expressly impious is the opinion of those who imagine that the Church of God can do without the study of those arts which, besides the prophetic books, are also taught by properly established schools. Without them, barbarism and ignorance of all good things will inevitably prevail in the human generation. However, nothing is less Christian than that enormous ignorance of the arts on which true culture is founded.

Yet nevertheless, the rhetorical doctrine and the arts, which secular writers also teach, must be used in such a way that they serve Christian doctrine and not rule over it. Paul reminds us of this in the second chapter of the Epistle to the Colossians, when he says: "See to it that no one deceives you through philosophy." He speaks, indeed, of the philosophy of Julian, Porphyry, and others who judged the Word of God according to philosophy, although it ought not to be queen but handmaid of the Word of God, to which everything must yield. Thus, just as the Moon receives its weaker light from the Sun, so philosophy—which is the doctrine of reason and a lesser light—must be governed by a higher light, and that is the Word of God. By it must be governed not only the limbs and other lower powers, but also the mind itself, whose light is philosophy.