We often meet with the most inconceivable notions. We are told quite seriously that the Church teaches, and that the Catholic has therefore to believe, that the earth is a flat disc surrounded by the sea, as the ancients believed; above it is a vault, below it hell-fire; that the earth stands still and the sun and stars revolve about it, just as _Ptolemy_ of Egypt taught; that God created the whole world just as it is now in exactly six days of twenty-four hours each; that He made the sun and moon, just as they are now illuminating the skies; that the strata, just as they now look when bared by the geologist’s hammer, even the coal-fields and petrified saurians and fossils—all were made, just as they now are, well nigh six thousand years ago. The Scriptures teach this, the Fathers of old and the theologians believe this: and that is where the Catholic must get his science. And then they are astonished, and consider dogma retreating before science, when they see other notions prevailing, when they see Catholic scientists defend without prejudice the evolution of the solar system, and even the system of the whole universe, from some primitive matter, or assume an organic evolution, as far as science supports it (cf. _Braun_, Ueber Kosmologie u. Standpunkt christlich. Wiss., 2d ed., 1906, etc.). They would be still more astonished perhaps to learn that similar ideas had long ago been proposed by _St. Augustine_ and _St. Thomas_ (cf. Summa c. G. l. 3, c. 77; _Knabenbauer_, in Stimmen a. M. Laach xiii, 75 _seq._). A distinction must be made between the teaching of the Church and the private views of individuals, schools, or periods. Only the teaching of the Church is the obligatory standard of Christian and Catholic thought, not the opinion of individuals. Hence not everything that Catholic savants have held to be true belongs to the teaching of the Church. Only when theologians unanimously declare something to be contained in the deposit of revealed truth, or the teaching of the Church,—only then is their teaching authoritative; not because it is the teaching of theologians, but because it is contained in revelation or the teaching of the Church. Else the maxim holds good: _Tantum valet auctoritas, quantum argumenta_. Nor is all that which a former age found in Holy Scripture, therefore to be believed as revealed truth, to the exclusion of all other interpretations.