The Divine Lamp

Section 5.  The Province of Revelation.

I.  Revelation embraces all those truths which have been revealed in any way whatever.
1.  Some revealed truths can be known only by means of Revelation; as, for example, the Blessed Trinity, the Incarnation, and Grace.  Others can e known by natural reason also; for instance, the Unity of God, Creation, and the Spirituality of the Soul.  The former, which are purely and simply matters of Faith, are revealed in order to be made known; whereas the latter are mentioned in Revelation to serve as a basis.
2.  Another important distinction is that between matters of Faith and matters of Morals.  Matters of Faith refer to God and His works, and are primarily of a speculative character.  Matters of morals refer to man and his conduct, for which they prescribe practical rules.

3.  A third distinction is between truths revealed for their own sake and truths revealed fro the sake of those.  This distinction is of great importance with regard to the content of Holy Writ.

4.  Lastly , some truths stand out clearly in Revelation, and are revealed in their completeness, while others can only be inferred by means of reflection and study.  The latter are called corollaries of the Faith, or theological truths.  It may come to pass that these may be proposed as matters of Faith by the Church, because they are necessary for the support of the Faith and also for the attainment of its object.
These four groups of revealed truths may not inaptly be compared to the different parts of a tree; the natural truths which serve as a basis are the roots; truths incidentally revealed are the bark which envelops and protects the trunk; truths inferred by ratiocination are the branches which spring from the trunk; while the practical truths are the buds and flowers, from which proceeds the fruit of Christian life.

II.  Although, strictly speaking, things revealed are alone the subject-matter of Faith, nevertheless many truths belonging to the domain of natural reason, but at the same time so connected and interwoven with Revelation that they cannot be separated from it, may also be reckoned as matter of Faith.  These truths are, as it were, the atmosphere in which the tree of Revelation lives and thrives.  The determination of the meaning of words used  for the expression of dogmas, and of passages in Holy Scripture and other documents, are instances.  In like manner many truths are inseparably connected with matters of morals, e.g. discipline, ceremonies, Religious Orders, the temporal power of the Pope, ect.