The argument, briefly sketched above, obliges us to rest the catholicity of the Church on the actual institution of Christ. We can, however, inquire into the essential reason of this institution. Does this reason lie simply in a free, voluntary determination of Christ, or in the interior essence of the Church herself? In the latter case, the Church would appear as Catholic, because the end of her establishment could be fulfilled under no other condition. There would be in her innermost being a secret determination, by force of which the idea of the Church is completely incapable of realization under any other form than that of catholicity. A Christian Church without the papacy were, therefore, entirely inconceivable. If this is actually the case, there lies hidden under the rind of the Church's visible form of catholicity, a still deeper catholicity, in which we are bound to recognize the most profound principle of the outward, historical side of catholicity. But that inward principle, the marrow of the Church, where are we to look for it? Our theologians, following St. Augustine, teach that the Church, like man, consists of soul and body. The theological virtues form the soul of the Church, and her body is constituted by the outward profession of the faith, the participation of the sacraments, and exterior connection with the visible head of the Church. [Footnote 11] St. Augustine, indeed, also designates the Holy Ghost as the soul or the inner principle of the Church. This is the same thought with the one which will be presently evolved, in which the inner principle of catholicity will be reduced to the conception of the _supernatural_. This, however, considered in itself, is withdrawn from the region of historical manifestation. In order that it may pass from the region of the invisible into that of apprehensible reality, it needs a medium that may connect together both orders, the invisible order of the supernatural and the order of historical manifestation. It is only in this {98} way that catholicity can acquire for itself a historical shape, and assume flesh and blood. [Footnote 11: Bellarm., _De Eccl. milit._, cap. ii.]