For this reason the Church is so often called in Holy Writ a body, and even the body of Christ - "Now you are the body of Christ" (I Cor. xii., 27)-and precisely because it is a body is the Church visible: and because it is the body of Christ is it living and energizing, because by the infusion of His power Christ guards and sustains it, just as the vine gives nourishment and renders fruitful the branches united to it. And as in animals the vital principle is unseen and invisible, and is evidenced and manifested by the movements and action of the members, so the principle of supernatural life in the Church is clearly shown in that which is done by it.
From this it follows that those who arbitrarily conjure up and picture to themselves a hidden and invisible Church are in grievous and pernicious error: as also are those who regard the Church as a human institution which claims a certain obedience in discipline and external duties, but which is without the perennial communication of the gifts of divine grace, and without all that which testifies by constant and undoubted signs to the existence of that life which is drawn from God. It is assuredly as impossible that the Church of Jesus Christ can be the one or the other, as that man should be a body alone or a soul alone. The connection and union of both elements is as absolutely necessary to the true Church as the intimate union of the soul and body is to human nature. The Church is not something dead: it is the body of Christ endowed with supernatural life. As Christ, the Head and Exemplar, is not wholly in His visible human nature, which Photinians and Nestorians assert, nor wholly in the invisible divine nature, as the Monophysites hold, but is one, from and in both natures, visible and invisible; so the mystical body of Christ is the true Church, only because its visible parts draw life and power from the supernatural gifts and other things whence spring their very nature and essence. But since the Church is such by divine will and constitution, such it must uniformly remain to the end of time. If it did nor, then it would not have been founded as perpetual, and the end set before it would have been limited to some certain place and to some certain period of time; both of which are contrary to the truth. The union consequently of visible and invisible elements because it harmonizes with the natural order and by God's will belongs to the very essence of the Church, must necessarily remain so long as the Church itself shall endure. Wherefore Chrysostom writes: "Secede not from the Church: for nothing is stronger than the Church. Thy hope is the Church; thy salvation is the Church; thy refuge is the Church. It is higher than the heavens and wider than the earth. It never grows old, but is ever full of vigour. Wherefore Holy Writ pointing to its strength and stability calls it a mountain" (Hom. De capto Eutropio, n. 6).
Also Augustine says: "Unbelievers think that the Christian religion will last for a certain period in the world and will then disappear. But it will remain as long as the sun - as long as the sun rises and sets: that is, as long as the ages of time shall roll, the Church of God - the true body of Christ on earth - will not disappear" (In Psalm. lxx., n. 8). And in another place: "The Church will totter if its foundation shakes; but how can Christ be moved?...Christ remaining immovable, it (the Church), shall never be shaken. Where are they that say that the Church has disappeared from the world, when it cannot even be shaken?" (Enarratio in Psalm. ciii., sermo ii., n. 5).
He who seeks the truth must be guided by these fundamental principles. That is to say, that Christ the Lord instituted and formed the Church: wherefore when we are asked what its nature is, the main thing is to see what Christ wished and what in fact He did. Judged by such a criterion it is the unity of the Church which must be principally considered; and of this, for the general good, it has seemed useful to speak in this Encyclical. ,
From this it follows that those who arbitrarily conjure up and picture to themselves a hidden and invisible Church are in grievous and pernicious error: as also are those who regard the Church as a human institution which claims a certain obedience in discipline and external duties, but which is without the perennial communication of the gifts of divine grace, and without all that which testifies by constant and undoubted signs to the existence of that life which is drawn from God. It is assuredly as impossible that the Church of Jesus Christ can be the one or the other, as that man should be a body alone or a soul alone. The connection and union of both elements is as absolutely necessary to the true Church as the intimate union of the soul and body is to human nature. The Church is not something dead: it is the body of Christ endowed with supernatural life. As Christ, the Head and Exemplar, is not wholly in His visible human nature, which Photinians and Nestorians assert, nor wholly in the invisible divine nature, as the Monophysites hold, but is one, from and in both natures, visible and invisible; so the mystical body of Christ is the true Church, only because its visible parts draw life and power from the supernatural gifts and other things whence spring their very nature and essence. But since the Church is such by divine will and constitution, such it must uniformly remain to the end of time. If it did nor, then it would not have been founded as perpetual, and the end set before it would have been limited to some certain place and to some certain period of time; both of which are contrary to the truth. The union consequently of visible and invisible elements because it harmonizes with the natural order and by God's will belongs to the very essence of the Church, must necessarily remain so long as the Church itself shall endure. Wherefore Chrysostom writes: "Secede not from the Church: for nothing is stronger than the Church. Thy hope is the Church; thy salvation is the Church; thy refuge is the Church. It is higher than the heavens and wider than the earth. It never grows old, but is ever full of vigour. Wherefore Holy Writ pointing to its strength and stability calls it a mountain" (Hom. De capto Eutropio, n. 6).
Also Augustine says: "Unbelievers think that the Christian religion will last for a certain period in the world and will then disappear. But it will remain as long as the sun - as long as the sun rises and sets: that is, as long as the ages of time shall roll, the Church of God - the true body of Christ on earth - will not disappear" (In Psalm. lxx., n. 8). And in another place: "The Church will totter if its foundation shakes; but how can Christ be moved?...Christ remaining immovable, it (the Church), shall never be shaken. Where are they that say that the Church has disappeared from the world, when it cannot even be shaken?" (Enarratio in Psalm. ciii., sermo ii., n. 5).
He who seeks the truth must be guided by these fundamental principles. That is to say, that Christ the Lord instituted and formed the Church: wherefore when we are asked what its nature is, the main thing is to see what Christ wished and what in fact He did. Judged by such a criterion it is the unity of the Church which must be principally considered; and of this, for the general good, it has seemed useful to speak in this Encyclical. ,