Let the author speak for himself. "The terms verum and factum, the true and the made, are used one for the other, in the Latin language, or, as the schoolmen say, are convertible. Intelligere, to understand, is the same as to read with clearness and to know with evidence. They used cogitare in the sense of the Italian pensare e andar raccogliendo; ratio with them meant a collection of numerical elements, and also the gift by which man is distinguished from, and made superior to, the brute. They defined man to be an animal participating of reason; animal rationis particeps: and consequently not absolutely possessed of it. As words are the signs of ideas, so also are ideas the signs and representations of things. Thus, as to read, legere, is to unite the elements of writing, which form the words; so to understand, intelligere, is to unite all the elements which constitute the perfect idea of anything. Hence we infer that the doctrine of the ancient Italians concerning truth was as follows: Truth is the same as fact; and consequently God is the first truth, because he is the first maker, factor; the infinite truth, because he made all things; the absolute truth, because he represents all the elements of things, both internal and external, for he contains them. To know is to unite the elements of things: hence it follows that thought, cogitatio, is a property of the human mind; and intelligence a property of the divine mind, because God contains all the internal and all the external elements of things, and therefore he unites them, and he it is that disposes them; whereas the human mind limited as it is, and separated from all that is not itself, may bring together extreme points, but cannot unite them; it may think of things, but cannot understand them; and this is why it is said to participate of reason, but not to possess it. Let us explain these ideas by a comparison. Divine truth is a solid image of things, a sort of plastic figure; human truth is an image on a plane, it has no depth, but is a sort of painting. Divine truth is true, because God knows in the same act by which he disposes and produces; human truth is in relation to things which man in like manner disposes and creates. Science is the cognition of the mode in which the thing is made; a cognition in which the mind makes its object, since it recomposes its elements. For God, who understands every thing, the object is a solid; but it is a surface for man who understands only the exterior. These points being settled, in order that we may more easily make them harmonize with our religion, let us observe that the ancient philosophers of Italy identified truth and fact, for they believed the world to be eternal. Thus the pagan philosophers adored a God who always operated ad extra, a point rejected by our theology. Wherefore in our religion, in which we profess that the world was created in time, and out of nothing, it is necessary to distinguish, and identify created truth with what is made, and uncreated truth with what is begotten, genito. Thus the Sacred Scriptures, with an elegance truly divine, give the name of the Word to the wisdom of God, which contains in itself the ideas of all things and the elements of these ideas. In the Word, truth is the comprehension of all the elements of this universe, and it might produce infinite worlds. From these elements, known and contained in the divine omnipotence, is formed the Word real and absolute, known by the Father from all eternity and begotten by him also from all eternity."[26]
295. From these principles Vico deduces some very transcendental consequences, among others, the explanation of the reason why our sciences are divided into many branches, and that of the different grades of certainty by which they are distinguished. Mathematics is the most certain, because a kind of creation of the intellect, which, starting with the unity of a point, constructs a world of forms and numbers by prolonging lines, and multiplying unity even to infinity. Thus it knows what it produces itself, and hence it is that the theorems commonly held to be objects of pure contemplation depend upon action just as the problems do. Mechanics is a less certain science than either geometry or arithemetic, because it considers motions as realized by machines; and physics is even less certain yet, because it does not, like mechanics, consider the external motion of circumferences, but the internal motion of their centres. There is still less certainty in sciences of the moral order, because these do not consider the motions of bodies arising from one certain and common origin, which is nature, but the motions of the soul, often most profound, often also capricious.
"Human science," he says, "owes its origin to a defect of the human mind; it is beyond all things in its extreme limitation, contains nothing of what it seeks to know, and is consequently unable to make the truth to which it aspires. The most perfect sciences are those which have expiated the vice of their origin, and are assimilated, as a creation, to divine science, that is, those in which the truth and the fact are mutually convertible.
"From what proceeds, we may infer that the criterion of truth, and the rule to recognize it, is to have made it: consequently, the clear and distinct idea of our mind which we have, is not a criterion of the truth, nor is it even a criterion of our mind; because the soul does not, by knowing itself, make itself; and not making itself, it knows not in what way it knows itself. Since human science takes abstraction for its basis, sciences are so much the more uncertain, as they more nearly approach corporal matter. …
"In a word, the true and the good are convertible, if what is known as true derives its being from the mind which knows it; as human science imitates divine science, wherein God, by knowing the true, begets it internally in eternity, and makes it externally in time. The communication of goodness to the objects of his thought is to God the criterion of the true: vidit Deus quod essent bona; to men it is to have made the truth which they know."[27]
296. Vico's system undeniably shows him to have been a profound thinker, and to have carefully meditated the problems of intelligence. His line dividing the certainty of sciences is exceedingly interesting. At first sight, nothing is more specious than the difference marked between mathematical, natural, and moral sciences. Mathematics is absolutely certain, because the work of the understanding, it is as the understanding, which constructed them, sees them to be. On the other hand, the natural and moral sciences regard objects independent of reason, having by themselves an existence of their own; wherefore, the understanding knows little of them, and even in this little it is the more liable to err as it penetrates deeper into a sphere where it cannot construct. We call this system specious, because when examined, it is found to be destitute of all solid foundation. We recognize, however, a profound thought in its author; for one he must have had to consider science under such a point of view.
297. The understanding knows only what it makes. This proposition sums up Vico's whole system; and it must have some foundation, or he cannot advance one step without begging his question. Why does the understanding know only what it makes? Why can the problem of representation have no possible solution out of causality? We think we have shown another origin besides this in identity, also in ideality duly connected with causality.
298. To understand is not to cause. There may be, and there really is, a productive intelligence; but the act of understanding and that of causing, in general, offer distinct ideas. Intelligence supposes an activity; otherwise that intimate life which distinguishes the intelligent being is inconceivable: but this activity does not produce the objects known; it operates in an immanent manner on these objects, presupposed to be either mediately or immediately in union with the intellect.
299. If the intellect be condemned to know nothing not made by itself, it is difficult to conceive how the act of understanding can commence. If we place ourselves in the initial moment, we shall not know how to explain the development of this activity; for, if it can only know what it has made, what is it to understand in the first moment before it has made any thing? In the system before us, the intellect has no object but what it has itself produced; but to understand, without an object understood, is a contradiction, so that not having in its initial moment yet produced any thing, there can be nothing understood; and, consequently, intelligence is inexplicable. We cannot suppose its activity to be blindly exercised: nothing is done blindly when there is question of representation, and the productive activity essentially relates to things represented as represented.