_Secchi_ was not the only priest and monk among the astronomers of the nineteenth century. The very first day of the century was made notable by the astronomical achievement of a monk. _Joseph Piazzi_, a member of the Theatine order (died 1826), discovered on that day the first asteroid, Ceres. The great mathematician _Gauss_ named his first born son Joseph, in _Piazzi’s_ honor. It is, indeed, a remarkable fact, testifying strongly against the incompatibility of natural science and faith, that just the Catholic clergy, the prominent representatives of religion and faith, have contributed a large contingent to the number of natural scientists. _Poggendorf’s_ Biographical Dictionary of the Exact Sciences contains, down to 1863, according to preface and recapitulation, the names and biographical sketches of 8,847 natural scientists. Of these, 862 are Catholic priests, amounting to 9.8 per cent. To appreciate these 10 per cent it must be taken into account that most of them were not connected with natural science by their position, but only through their personal interest, and most of them were engaged in other duties. Mathematics, although not natural science proper, is inseparably connected with it. For this reason we may extend our consideration to mathematicians. We only point to the three greatest, _Euler_, _Gauss_, and _Cauchy_, and all three were religious men. _Euler_ (died 1783 at Petersburg) has no peer in the recent history of science in prolific activity: ten times he was awarded the prize by the Paris Academy of Sciences. _Cantor_ says of him: “Like most great mathematicians, _Euler_ was profoundly religious, though without bigotry. He personally conducted every evening the private devotions at his home, and one of the few polemical books he wrote was a defence of revelation against the objections of free-thinkers.” Its publication at Berlin in 1747, in close proximity of the court of _Frederick the Great_, presupposed a certain moral courage. In this book he refers to the difficulties found in all sciences, even in geometry, adding: “By what right then can the free-thinkers demand of us to reject at once Holy Writ in its entirety, because of some difficulties which frequently are not even so important as those complained of in geometry?” _Gauss_ (died 1855) is perhaps the greatest mathematician of all times. It sounds incredible, yet it is well attested, that as a child of three years, when in the workshop of his father, a plain mechanic, he was able to correct the father if he made a mistake in figuring out the wages paid to his journeymen. His biographer, _Waltershausen_, says of him: “The conviction of a personal existence after death, the firm belief in an ultimate Ruler of things, in an eternal, just, all-wise and all-powerful God, formed the foundation of his religious life, which, with his unsurpassed scientific researches,