"The canvas," say the adversaries of innate ideas, is all white, "and in proof witness the unceasing labor of the artist to cover it with figures." But does their doctrine, forsooth, suppose that nothing exists before experience? Do they admit man to be the simple work of instruction, of education? Do they maintain that our interior world is nothing more than a series of phenomena caused by impressions, and that it would have been other than what it is, had it had other impressions? Most certainly not. They admit: first, an inward activity excited and improved by sensible experience: secondly, the necessity of first principles as well intellectual as moral: thirdly, an interior light, to enable us to see them when presented, and to assent to them by an irresistible necessity. We find the words, "Signatum est super nos lumen vultus tui Domine," cited upon every page of those authors. 194. Saint Thomas says that first principles, as well speculative as practical, must be naturally communicated to us: "Oportet igitur _naturaliter nobis esse indita_, sicut principia speculabilium, ita et principia operabilium."[13] In another place, inquiring whether the soul knows immaterial things in their eternal reasons, (in rationibus æternis,) he says that the intellectual light which is within us, is nothing else than a certain participated likeness of the uncreated life, in which the eternal reasons are contained: "Ipsum enim lumen intellectuale, quod est in nobis nihil est aliud, quam quædam participata similitudo luminis increati, in quo continentur rationes æternæ."[14] [13] P. I., Q. L. XXIX. A. 12. [14] _Ib.,_ Q. L. XXXIV. A. 5. 195. We find it, in these passages, expressly taught that there is within us something besides what we have acquired by experience, in which point the scholastics all agree with the defenders of innate ideas. The difference between them is this: the former do not consider the intellectual light to suffice for knowledge, if the forms or _species_ upon which it may reflect are wanting; the latter distinguish the light from the colors, and them they make originate in the light itself. 196. The question of innate ideas, so warmly contested in the schools of philosophy, would never have presented so great difficulties, had it been stated with proper clearness. To do this it was necessary to classify the inward phenomena called ideas in a corresponding manner, and to determine with accuracy the sense of the word _innate_.