The Church in its traditional form thus stands forth armed with the spear of the Mass, the shield of the Hierarchy, and the helmet of the Papacy; and perhaps the subconscious purpose –or the divine intention, if you prefer that language– of this heavy panoply of institutions in which the Church has clad herself is the very practical one of outlasting the toughest of the secular institutions of this world, including all the civilizations. If we survey all the institutions of which we have knowledge in the present and in the past, I think that the institutions created, or adopted and adapted, by Christianity are the toughest and the most enduring of any that we know and are therefore the most likely to last –and outlast all the rest. The history of Protestantism would seem to indicate that the Protestant act of casting off this armour four hundred years ago was premature; but that would not necessarily mean that this step would always be a mistake; and , however that may be, the institutional element in the traditional Catholic form of the Church Militant on Earth, even if it proves to be an invaluable and indispensable means of survival, is all the same a mundane feature which makes the Church Militant’s life different from that of the Kingdom of Heaven, in which they neither marry nor are given in marriage but are as the angels of God, and in which each individual soul catches the spirit of God from direct communion with Him –‘like light caught from a leaping flame,’ as Plato puts it in his Seventh Letter.
Thus, even if the Church had won a fully world-wide allegiance and had entered into the inheritance of the last of the civilizations and of all the other higher religions, the Church on Earth would not be a perfect embodiment here on Earth of the Kingdom of Heaven. The Church on Earth would still have sin and sorrow to contend with as well as to profit by as a means of grace on the principle of ?Ueae iUeio, and she would still have to wear for a long time to come a panoply of institutions to give her the massive social solidity that she needs in the mundane struggle for survival, but this at the inevitable price of spirituality weighing her down, On this showing, the victorious Church Militant on Earth will be a province of the Kingdom of God, but a province in which the citizens of the heavenly commonwealth have to live and breathe and labour in an atmosphere that is not their native element.
The position in which the Church would then find herself is well conveyed in Plato‘s conceit, in the Phaedo, of the true surface of the Earth. We live, Plato suggests, in a large but local hollow, and what we take to be the air is really a sediment of fog. If one day we could make our way to the upper levels of the surface of the Earth, we should there breathe the pure ether and should see the light of the Sun and stars direct; and then we should realize how dim and blurred had been our vision down in the hollow, where we see the heavenly bodies, through the murky atmosphere in which we breathe, as imperfectly as the fishes see them through the water in which they swim. This Platonic conceit is a good simile for the life of the Church Militant on Earth; but the truth cannot be put better than it has been by Saint Augustine.