The confusion arising from the uncertainty in the use of these words had been the cause of strife throughout the Christian Church for more than twenty years before the date of Cyril’s Lectures; and though it was declared at the Council of Alexandria (362) to be but a controversy about words Athan. Tomus ad Antiochenos, §§ 5, 6., it had long been and long afterwards continued to be a fruitful cause of dissension between men who, when forced to explain their meaning, were found to be in substantial agreement.  That Cyril abstained from introducing into his elementary teaching terms so provocative of dangerous controversy, is a reason for commendation, not for censure.  But if it is alleged that he denied or doubted or failed to assert the essential Godhead of the Son, the suspicion is unfounded and easily refuted.  To the many passages already quoted concerning the eternal generation of the Son, it will be enough to add one single sentence which ought to dispel all doubt of his orthodoxy.  “The Only-begotten Son, together with the Holy Ghost, is partaker of the Godhead of the Father (τῆς θεότητος τῆς Πατρικῆς κοινωνός).”  The word chosen by Cyril to express the Divine Essence (θεότης) common to the three Persons of the Godhead is at least as appropriate as οὐσία.