17 Yet, it would be a great mistake to suppose that, given these theories, one is authorised to believe that faith and science are independent of one another. On the side of science the independence is indeed complete, but it is quite different with regard to faith, which is subject to science not on one but on three grounds. For in the first place it must be observed that in every religious fact, when you take away the divine reality and the experience of it which the believer possesses, everything else, and especially the religious formulas of it, belongs to the sphere of phenomena and therefore falls under the control of science. Let the believer leave the world if he will, but so long as he remains in it he must continue, whether he like it or not, to be subject to the laws, the observation, the judgments of science and of history. Further, when it is said that God is the object of faith alone, the statement refers only to the divine reality not to the idea of God. The latter also is subject to science which while it philosophises in what is called the logical order soars also to the absolute and the ideal. It is therefore the right of philosophy and of science to form conclusions concerning the idea of God, to direct it in its evolution and to purify it of any extraneous elements which may become confused with it. Finally, man does not suffer a dualism to exist in him, and the believer therefore feels within him an impelling need so to harmonise faith with science, that it may never oppose the general conception which science sets forth concerning the universe. Thus it is evident that science is to be entirely independent of faith, while on the other hand, and notwithstanding that they are supposed to be strangers to each other, faith is made subject to science. All this, Venerable Brothers, is in formal opposition with the teachings of Our Predecessor, Pius IX, where he lays it down that: In matters of religion it is the duty of philosophy not to command but to serve, but not to prescribe what is to be believed but to embrace what is to be believed with reasonable obedience, not to scrutinise the depths of the mysteries of God but to venerate them devoutly and humbly. The Modernists completely invert the parts, and to them may be applied the words of another Predecessor of Ours, Gregory IX., addressed to some theologians of his time: Some among you, inflated like bladders with the spirit of vanity strive by profane novelties to cross the boundaries fixed by the Fathers, twisting the sense of the heavenly pages . . .to the philosophical teaching of the rationals, not for the profit of their hearer but to make a show of science . . . these, seduced by strange and eccentric doctrines, make the head of the tail and force the queen to serve the servant.
Source: Pascendi Dominici Gregis (Vatican.va)