Thus the two swords of which Christ said, 'It is enough,' became the spiritual and temporal powers, and the grant of the spiritual to Peter involves the supremacy of the Papacy[141]. Thus one writer proves the eternity of Rome from the seventy-second Psalm, 'They shall fear thee as long as the sun and moon endure, throughout all generations;' the moon being of course, since Gregory VII, the Roman Empire, as the sun, or greater light, is the Popedom. Another quoting, 'Qui tenet teneat donec auferatur[142],' with Augustine's explanation thereof[143], says, that when 'he who letteth' is removed, tribes and provinces will rise in rebellion, and the Empire to which God has committed the government of the human race will be dissolved. From the miseries of his own time (he wrote under Frederick III) he predicts that the end is near. The same spirit of symbolism seized on the number of the electors: 'the seven lamps burning in the unity of the sevenfold spirit which illumine the Holy Empire[144].' Strange legends told how Romans and Germans were of one lineage; how Peter's staff had been found on the banks of the Rhine, the miracle signifying that a commission was issued to the Germans to reclaim wandering sheep to the one fold. So complete does the scriptural proof appear in the hands of mediæval churchmen, many holding it a mortal sin to resist the power ordained of God, that we forget they were all the while only adapting to an existing institution what they found written already; we begin to fancy that the Empire was maintained, obeyed, exalted for centuries, on the strength of words to which we attach in almost every case a wholly different meaning. [Sidenote: Illustrations from Mediæval Art.] It would be a task both pleasant and profitable to pass on from the theologians to the poets and artists of the Middle Ages, and endeavour to trace through their works the influence of the ideas which have been expounded above. But it is one far too wide for the scope of the present treatise; and one which would demand an acquaintance with those works themselves such as only minute and long-continued study could give. For even a slight knowledge enables any one to see how much still remains to be interpreted in the imaginative literature and in the paintings of those times, and how apt we are in glancing over a piece of work to miss those seemingly trifling indications of the artist's thought or belief which are all the more precious that they are indirect or unconscious. Therefore a history of mediæval art which shall evolve its philosophy from its concrete forms, if it is to have any value at all, must be minute in description as well as subtle in method. But lest this class of illustrations should appear to have been wholly forgotten, it may be well to mention here two paintings in which the theory of the mediæval empire is unmistakeably set forth. One of them is in Rome, the other in Florence; every traveller in Italy may examine both for himself.