Our object is to give a comprehensive and detailed history of the vicissitudes of this festival, while leaving aside the history of the doctrine. Naturally they cannot be kept entirely distinct, still the latter shall only be touched upon in so far as is necessary for the elucidation of the history of the feast.[523] Passaglia and his collaborator Clemens Schrader, S.J., in their well known work, “_De Immaculato Deiparæ Conceptu_” (Rome, 1854 and 1855, 3 vols. 4to.), have given us a rich and noteworthy collection of materials for this purpose. We must do justice to the immense learning expended upon this work both in its dogmatic and historical sections, but the historical explanations can no longer be regarded as satisfactory. On the one hand, subsequent investigations have brought fresh facts to light which give a new turn to the history; and, on the other, Passaglia was deficient in the critical faculty, and merely in order to marshal as many proofs as possible, he made use of several which cannot stand close investigation, and must be set aside if the whole question is not to be misrepresented. For the correct understanding and examination of the sources of evidence, it must first be observed that anciently both among the Greeks and the Latins the term _conceptio_ (σύλληψις) was taken in the active sense, while we are accustomed to take it in the passive sense. _Conceptio Mariæ Virg._ signified then the conception of Christ by Mary, while the (passive) conception of Mary was called the _Conceptio S. Annæ_.