This is clearly stated by the recent encyclical _Pascendi_: “In judging of pious traditions, the following must be kept in mind: the Church employs such prudence in treating of these matters that she does not allow such traditions to be written about except with great precaution and only after making the declarations required by _Urban VIII._; and even then, after this has been properly done, the Church by no means asserts the truth of the private revelation or of the tradition, but merely permits them to be believed, provided there be sufficient human reasons. It was in this sense that the Sacred Congregation of Rites declared thirty-one years ago: ‘These apparitions are neither approved nor condemned by the Holy See; it merely permits them to be believed in a natural way, provided the tradition on which they rest be corroborated by credible testimonies and documents.’ Whoever follows this maxim is safe. The veneration of such things is always conditional, it is only relative, and on the condition that the tradition be true. In so far only is the veneration absolute as it relates to the Saint to whom the veneration is paid. The same applies to the veneration of relics.” (_Benedict XIV._ says of private revelations: “Praedictis revelationibus etsi _approbatis_, non debere nec posse a nobis adhiberi assensum fidei catholicae, sed tantum fidei humanae juxta regulas prudentiae, juxta quas praedictae revelationes sunt probabiles et pie credibiles.” De Serv. Dei beatificatione, III, c. ult. n. 15). Hence the historian is free to investigate such traditions critically, provided, of course, that he does not violate the reverence due to sacred things. 4. Infallible and Non-Infallible Teachings. Now to consider a last point. Does it not rest entirely with the pleasure of ecclesiastical authority, as would seem from what has been said above, to suppress at any time the results, or at least the hypotheses, of scientific research by pointing to putative truths of faith presumed to be in opposition? Then, of course, the scientist would be at the mercy of a zealous ecclesiastical authority. Or will it perhaps be said that this authority is infallible in its every decision? Think of _Galileo_, of the interdict against the Copernican view of the world, and you will be able fully to appreciate the danger alluded to! We shall later on return to the famous case of _Galileo_. For the present we only call attention to a distinction which must not be overlooked, the distinction between infallible teachings and those that are not infallible.(3)