6 Its solid foundations having been thus laid, a perpetual and varied service is further required of philosophy, in order that sacred theology may receive and assume the nature, form, and genius of a true science. For in this, the most noble of studies, it is of the greatest necessity to bind together, as it were, in one body the many and various parts of the heavenly doctrines, that, each being allotted to its own proper place and derived from its own proper principles, the whole may join together in a complete union; in order, in fine, that all and each part may be strengthened by its own and the others' invincible arguments. Nor is that more accurate or fuller knowledge of the things that are believed, and somewhat more lucid understanding, as far as it can go, of the very mysteries of faith which Augustine and the other fathers commended and strove to reach, and which the Vatican Council itself(20) declared to be most fruitful, to be passed over in silence or belittled. Those will certainly more fully and more easily attain that knowledge and understanding who to integrity of life and love of faith join a mind rounded and finished by philosophic studies, as the same Vatican Council teaches that the knowledge of such sacred dogmas ought to be sought as well from analogy of the things that are naturally known as from the connection of those mysteries one with another and with the final end of man.(21)
Source: Aeterni Patris (Vatican.va)