But, it is to be observed, that it is not only necessary that a Church should preserve the true Order in the Ministry, but also that it retain the true faith. For a true faith and true Order are both necessary to constitute a Church. All the heretical sects of the ancient Church had the Apostolic Ministry; but, when they departed from the true faith, they were excluded from the communion of the Church. “The Arians, the Donatists, the Novatians, &c. &c., were all Episcopal in their Ministry, and in this respect differed in nothing from the Orthodox Catholic Church. Their grand error lay in the want of that union of Order _and_ Faith, which are essential to the being of a Church.” An external commission, conveyed by Episcopal consecration or ordination, is considered necessary to constitute a lawful ministry; and it is therefore declared, by the Church, that “no man shall be accounted or taken to be a lawful Bishop, Priest, or Deacon, in this Church, or suffered to execute any of said functions,” unless he has “had Episcopal consecration or ordination;” and the power of ordaining, or setting apart to the ministry, and of laying on hands upon others, is vested in the Bishops. The _ministry_ is of Divine appointment, and consists of three orders, only,—Bishop, Priest, and Deacon. The _government_ is of human regulation, and may be modified as circumstances require. Other officers may be appointed, and the manner in which ministers are invested with their jurisdiction may be varied. To use the language of the Episcopal Church in the United States, in the Preface to her Book of Common Prayer, “It is a most invaluable part of that blessed liberty, wherewith Christ hath made us free, that, in His worship, different forms and usages may, without offence, be allowed, provided the substance of the faith be kept entire; and that, in every Church, what cannot be clearly determined to belong to Doctrine, must be referred to Discipline; and therefore, by common consent and authority, may be altered, abridged, enlarged, amended, or otherwise disposed of, as may seem most convenient for the edification of the people, ‘according to the various exigencies of times and occasions.’ ... The particular Forms of Divine Worship, and the Rites and Ceremonies appointed to be used therein, being things in their own nature indifferent and alterable, and so acknowledged, it is but reasonable, that, upon weighty and important considerations, according to the various exigencies of times and occasions, such changes and alterations should be made therein, as to those, who are in places of authority should, from time to time, seem either necessary or expedient.”