Therefore faith can only tell the profane scientist that he must not assert anything which is held by faith to be erroneous; that it is false to say there is nothing but force and matter, that the human soul ends in death, or that the various families of the human race have not a common origin. As soon as the scientist knows by faith that a thing is false, he is bound to refrain from asserting it: bound in the first place by the duty to believe, but also by the principles of his own science, which is to find not error, but truth, which forbids to assert what has been proved to be erroneous. Perhaps his own means will not enable him to prove the truth independently of revelation; then from the standpoint of his science he must say, _Non liquet._ The position of the Catholic Church agrees with these principles. She knows, and emphasizes that science has its own method, and hence a natural right and freedom to proceed in its own field according to its method. The Church rejects but one kind of freedom, viz., the freedom to propound a doctrine proved by faith to be erroneous. “The Church by no means forbids these disciplines to use in their own field their own principles and method,” declares the Vatican Council. “But, while acknowledging this lawful freedom, the Church takes care to prevent them from taking up errors in opposition to divine teaching, or from creating confusion by transgressing their limits and invading the realm of faith” (Vat. sess. III, ch. 4. Cf. also the letter of _Pius IX_., “Gravissimas,” of Dec. 11, 1862, to the Archbishop of Munich, Denz. n. 1666, _seq._) These few remarks show the lack of intelligence in the charge that “Catholic philosophy starts from dogmas and revelation,” or that the Church would dictate to scientists everything they should teach; that, according to its principles it could claim the right “to impose upon a physicist of _Zeppelin’s_ era the task of proving the Ascension of Christ or the Assumption of Mary by aërostatic rules.” This is simply gross ignorance or misrepresentation. 3. Restraint Only in the Province of Revelation.