In the second place, we have to contend against those who, abusing their knowledge of physical science, minutely scrutinize the Sacred Books, in order to detect the writers in a mistake, and so to vilify the books themselves. Attacks of this kind, bearing as they do on matters of experience of the senses, are peculiarly dangerous to the masses, and also to the young, who are but beginning their literary studies. The young, if they lose their reverence for divine revelation on any one point, are but too easily led to give up believing in revelation altogether. It need scarcely be pointed out how the science of nature, just as it is so admirably adapted to show forth the glory of the Great Creator, provided it be rightly taught, so, if it be perversely imparted to the youthful intelligence, it may prove most fatal in destroying the principles of true philosophy, and in the corruption of morality. Hence to the professor of Sacred Scripture a knowledge of natural science will be of the greatest service in detecting and meeting such attacks upon the Sacred Books.
There can never, indeed, be any real discrepancy between the theologian and the physicist, as long as each confines himself within his own lines, and so long as both are careful, as St. Augustine warns us, "not to make rash assertions, or to assert that which is not known as if it were really known." If dissension should arise between them, here is the rule, laid down by St. Augustine for the theologian: "Whatever they can really demonstrate to be true of physical nature, we must show to be not contrary to our Scriptures. Whatever they assert in their treatises which is contrary to these Scriptures of ours, that is, to Catholic faith, we must either prove it, as well as we can, to be entirely false, or at all events we must, without the smallest hesitation, believe it to be so." To understand how just is the rule here formulated we must remember, first, that the sacred writers, or, to speak more accurately, the Holy Ghost, who spoke by means of them, did not intend to teach men those things (that is to say, the essential nature of the things of the visible universe)--things which are in no way profitable unto salvation. The sacred writers did not seek to penetrate the secrets of nature. They rather described and dealt with things in more or less figurative language, or in terms which were commonly used at the time, and terms which in many instances are in daily use at this day, even amongst the most eminent men of science. Ordinary speech primarily and properly describes that which falls under the senses. Somewhat in the same way the sacred writers--as the Angelic Doctor reminds us--"went by what sensibly appeared," or put down that which God, speaking to men, signified in a way which men could understand, and to which they were accustomed.