Hence if the critic of the Bible presupposes miracles and prophecies to be impossible, inferring therefrom that many narratives in Holy Writ cannot be authentic, but must be legends of a later period, he is making arbitrary presuppositions, he is not an unprepossessed scientist. Likewise, if an historian presupposing God’s supernatural providence over the world to be impossible, and, in building upon this basis, comes to the conclusion that the Christian religion grew from purely natural factors, from Oriental notions and myths, from Greek philosophy and Roman forms of government, he again makes unproved suppositions. If the natural philosopher assumes that there cannot be a personal Creator, and infers from it that the world is of itself and eternal, he has forfeited the claim of being an unprepossessed scientist, and by making in any way his own pet ideas the basis of his research he is violating the demands of unprepossession; the results he arrives at are not scientific results, but the speculations of an amateur. Unprepossession and Religious Conviction. Is it possible for the Christian scientist who adheres to his faith, to be unprepossessed, as demanded by science? According to all that has been said hitherto about the relation of science to faith, the answer can be only in the affirmative. The believing Christian and Catholic looks upon the doctrines of faith taught him by revelation and the Church as an _established truth_. What to me is true and certain I can take for the true and certain basis and standard of my thought. This is demanded by unprepossession—nothing more. Considering the immense extent of the sciences, the profane sciences will but seldom, and in but few matters, have occasion to presuppose truths of faith in the above-mentioned way; and only in a negative form at that. We have previously shown that the profane sciences must never take truths of faith for a positive basis to build upon; they must regard the doctrines of revelation only in so far as it is not allowed to teach anything in contradiction to them. And with this demand they will meet in rare instances only, because, if not overstepping their province, they will very seldom come in touch with faith (cf. pp. 88-96). When _Kepler_ was studying his planetary orbits, and _Newton_ discovered the law of gravitation, both worked independent of the Christian view of the world which they both professed; it was in no way a necessary presupposition to their research. When _Scheiner_ discovered the sun-spots, and _Secchi_ classified the spectra of the stars, they were not doing so as Jesuits nor as Catholics; as Mohammedans or atheists they might have made the same discoveries. Steam engines and railways, _Volta’s_ electricity, cathode-rays and X-rays, all discoveries that the nineteenth century can boast of, do not depend directly on any special view of the world.