17. It is of capital importance that the students of your senior seminaries should study, for at least two years, with great care, "rational" philosophy, which, as the learned Benedictine Mabillon, the glory of his order and of France, used to say, will be of the greatest assistance to them, not only in teaching them how to reason well and arrive at right conclusions, but in putting them in a position to defend the orthodox faith against the captious and often sophistical arguments of adversaries.¹⁰