How entirely independent in themselves are their constituent parts! On the one hand, earthly might, grounded indeed in right but ruling by force, cemented by riches, carrying the sword of life and death in its hands, exulting in all the vast accumulation of human arts and sciences, the work of civilised man through long ages; on the other hand, a royal priesthood, with a divine truth, carried through the ages by an order of men generated spiritually in virtue of the consecration once given by the hands of Christ to Peter and his brethren. The temporal government marked by wealth and force; the spiritual by poverty and weakness. Yet both reign over the soul and body of man individual and collective. These powers are both ordained by God; can they be also ordained with co-ordination?
The following passage of St. Thomas[27] leads, I think, to a full answer to this question:—
"As the life by which men live well here on earth is as means to the end of that blessed life which we hope for in heaven, so whatever particular goods are obtained by man's agency, as, for instance, riches, profits of trade, health, eloquence, or learning, have for their end the good of the mass. If then, as we have before shown, the person charged with the care of the last end ought to be the superior of those who are charged with means to an end, and to direct them by his authority, it is evident from what we have said that, just as the king ought to be subject to that domain and regimen which is administered by the office of the priesthood, so he ought to preside over all human offices and regulate them by his supreme authority. Now whoever has the duty of doing anything which stands to another thing as means to an end, is bound to see that his work is suitable to that end; so the armourer furbishes his sword for fighting, and the builder arranges his house to be lived in. Since, then, the beatitude of heaven is the end of that life by which we live at present virtuously, the king's office requires him to promote such a life in his people as is suitable for the attainment of blessedness in heaven, by ordaining what tends thither, and by forbidding, so far as is possible, the contrary."
The king will here stand for whoever has sovereign authority. That sovereign authority therefore is itself subject to the law of God through all its exercise. The bearer of that law of God is the Spiritual Power which stands over against all sovereigns, in all countries, with the commission placed expressly in its hands by Christ. So far, therefore, as the law of God is concerned, which is precisely the same for the individual and the multitude, the sovereign is in every country subject to it, and the more stringently because, in the words of St. Thomas, he presides over all _human_ offices. These by their nature are subject to the _superhuman_ office.