Herman Bavinck, Reformed Dogmatics, v.1, p. 233
…in every science we may discern three fundamental principles. Here, too, God is the first principle of being (principium essendi); present in his mind are the ideas of all things; all things are based on thoughts and are created by the word. It is his good pleasure, however, to reproduce in uman beings made in his image an ectypal knowledge that reflects this archetypal knowledge (cognitio archetypa) in his own divine mind. He does this, not by letting us view the ideas in his being (Malebranche) or by passing them all on to us at birth (Plato, the theory of innate ideas), but by displaying them to the human mind in the works of his hands. The world is an embodiment of the thoughts of God; it is “a beautiful book in which all creatures, great and small, are as letters to make us ponder the invisible things of God” (art. 2, Belgic Confession). It is not a book of blank pages in which, as the idealists would have it, we human beings have to write down the words but a “reader” in which God makes known to us what he has recorded there for us. Accordingly, the created world is the external foundation of knowledge (principium cognoscendi externum) for all science.
But that is not enough. We need eyes in order to see. “If our eyes were not filled with sunshine, how could we see the light?” There just has to be correspondence or kinship between object and subject. The Logos who shines in the world must also let his light shine in our consciousness. That is the light of reason, the intellect, which, itself originating in the Logos, discovers and recognizes the Logos in things. It is the internal foundation of knowledge (principium cognoscendi internum). Just as knowledge within us is the imprint of things upon our souls, so, in turn, forms do not exist except by a kind of imprint of the divine knowledge in things. So, in the final analysis, it is God alone who from his divine consciousness and by way of his creatures conveys the knowledge of truth to our mind—the Father who by the Son and in the Spirit reveals himself to us. “There are many who say, ‘O that we might see some good!’ Let the light of your face shine on us, O Lord!” (Ps. 4:6).
Louis Berkhof, Systematic Theology, pp.93-95
PRINCIPIA OF THE NON-THEOLOGICAL SCIENCES. These are the following three:
a. God is the principium essendi. God is the source and fountain of all our knowledge. He possesses an archetypal knowledge of all created things, embracing all the ideas that are expressed in the works of His creation. This knowledge of God is quite different from that of man. While we derive our knowledge from the objects we perceive, He knows them in virtue of the fact that He has from eternity determined their being and form. While we attain to a scientific insight into things and relations only by a laborious process of discursive thought, He has an immediate knowledge of all things, and knows them not only in their relations but also in their very essence. And even so our knowledge is imperfect, while His knowledge is all-comprehensive and perfect in every way. We are only partly conscious of what we know, while He is always perfectly conscious of all His knowledge. The fulness of the divine knowledge is the inexhaustible source of all our knowledge, and therefore God is the principium essendi of all scientific knowledge. Naturally, Pantheism with its impersonal and unconscious Absolute cannot admit this, for a God, who has no knowledge Himself, can never be the principle or source of our knowledge. In fact, all absolute Idealism would seem to involve a denial of this principle, since it makes man an autonomous source of knowledge. The origin of knowledge is sought in the subject; the human mind is no more a mere instrument, but is regarded as a real fons or source.
b. The world as God’s creation is the principium cognoscendi externum. Instead of “the world as God’s creation” we might also say “God’s revelation in nature.” Of His archetypal knowledge God has conveyed an ectypal knowledge to man in the works of His hands, a knowledge adapted to the finite human consciousness. This ectypal knowledge is but a faint reproduction of the archetypal knowledge found in God. It is on the one hand real and true knowledge, because it is an imprint, a reproduction, though in temporal and therefore limited forms, of the knowledge of God. On the other hand it is, just because it is ectypal, no complete knowledge, and since sin put its stamp on creation, no perfectly clear nor absolutely true knowledge. God conveyed this knowledge to man by employing the Logos, the Word, as the agent of creation. The idea that finds expression in the world is out of the Logos. Thus the whole world is an embodiment of the thoughts of God or, as Bavinck puts it, “a book in which He has written with large and small letters, and therefore not a writing-book in which we, as the Idealists think, must fill in the words.” God’s beautiful creation, replete with divine wisdom, is the principium cognoscendi externum of all non-theological sciences. It is the external means by which the knowledge that flows from God is conveyed to man. This view of the matter of is, of course absolutely opposed to the principle of Idealism, that the thinking man creates and construes his own world: not only the form of the world of thought (Kant), but also its material and contents (Fichte), and even the world of being (Hegel).
c. Human reason is the principium cognoscendi internum. The objective revelation of God would be of no avail, if there were no subjective receptivity for it, a correspondence between subject and object. Dr. Bavinck correctly says: “Science always consists in a logical relation between subject and object.” It is only when the subject is adapted to the object that science can result. And God has also provided for this. The same Logos that reveals the wisdom of God in the world is also the true light, “which lighteth every man coming into the world.” Human reason with its capacity for knowledge is the fruit of the Logos, enables man to discover the divine wisdom in the world round about him, and is therefore the principium cognoscendi internum of science. By means of it man appropriates the truth revealed in creation. It is not satisfied with an aphoristic knowledge of details, but seeks to understand the unity of all things. In a world of phenomena which are many and varied, it goes in quest of that which is general, necessary, and eternal,—the underlying fundamental idea. It desires to understand the cause, the essential being, and the final purpose of things. And in its intellectual activity the human mind is never purely passive, or even merely receptive , but always more or less active. It brings with it certain general and necessary truths, which are of fundamental significance for science and cannot be derived from experience. This thought is denied by Empiricism in two different ways: (1) by regarding the human spirit as a tabula rasa and denying the existence of general and necessary truths; and (2) by emphasizing analytical experience rather than synthetic reason. Dr. Bavinck points out that it ended in Materialism. Says he: “First the thought-content, then the faculty, and finally also the substance of the spirit is derived from the material world.”