St. Thomas adds, indeed, "Sed indiget demonstrari, per ea quae sunt magis nota quoad nos, et minus secundam naturam, scilicet per effectus;" but this is easily explained. The saint argues that it is not self-evident that God is, because it is not self-evident what he is; for, according to the scholastic philosophy, to be able to affirm that a thing is, it is necessary to know its quidity [Footnote 40], since without knowing what the thing is we cannot know that it is. What God is can be demonstrated only by his works, and that it can be so demonstrated St. Paul assures us, Rom. 1:20: "Invisibilia ipsius, a creatura mundi, per ea quae facta sunt, intellecta, conspiciuntur: sempiterna quoqne virtus et divinitas;" or as we venture to English it: "The invisible things of God, even his eternal power and divinity, are clearly seen from the foundation of the world, being understood (or known) by the things that are made." St. Paul appeals to the things that are made not to prove that God is, but to show what he is, or rather, if we may so express ourself, to prove that he is God, and leaves us, as does St. Thomas, to prove, with St. Augustine, St. Anselm, Fénelon, and others, that he is, by the argument derived from intuitive ideas, or first principles, commonly called the _argumentum a priori_, though that, strictly speaking, it is not, for there is nothing more ultimate or universal in science than is God himself, or, rather, that which is God. [Transcribers footnote 40: quidity--Real nature of a thing; the essence.] {159} The ideal formula is true, for it is contained in the first verse of Genesis, "In the beginning God created heaven and earth," and in the first article of the creed, "I believe in one God, maker of heaven and earth, and all things visible and invisible;" and what it formulates is, as we have shown, and as is shown more at length in "The Problems of the Age," intuitive, and the human mind could not exists and operate if it were not so; but the formula itself, or, rather, the formulation as an intellectual judgment, is not so. The judgment was beyond the reach of all Gentile philosophy, which nowhere asserts or recognizes the fact of creation; it is beyond the reach of the mass even of the Christian people, who hold that God creates the world as an article of faith rather than as a scientific truth; it is denied by nearly all the systems of philosophy constructed by non-Catholics even in our own day, and it may well be doubted if science, unaided by revelation, could ever have attained to it.