The analogy between the lights of heaven and the princes of earth is one which mediæval writers are very fond of. It seems to have originated with Gregory VII. [322] Typifying the spiritual and temporal powers. Dante meets this by distinguishing the homage paid to Christ from that which his Vicar can rightfully demand. CHAPTER XVI. THE CITY OF ROME IN THE MIDDLE AGES. 'It is related,' says Sozomen in the ninth book of his Ecclesiastical History, 'that when Alaric was hastening against Rome, a holy monk of Italy admonished him to spare the city, and not to make himself the cause of such fearful ills. But Alaric answered, "It is not of my own will that I do this; there is One who forces me on, and will not let me rest, bidding me spoil Rome[323]."' Towards the close of the tenth century the Bohemian Woitech, famous in after legend as St. Adalbert, forsook his bishopric of Prague to journey into Italy, and settled himself in the Roman monastery of Sant' Alessio. After some few years passed there in religious solitude, he was summoned back to resume the duties of his see, and laboured for awhile among his half-savage countrymen. Soon, however, the old longing came over him: he resought his cell upon the brow of the Aventine, and there, wandering among the ancient shrines, and taking on himself the menial offices of the convent, he abode happily for a space. At length the reproaches of his metropolitan, the archbishop of Mentz, and the express commands of Pope Gregory the Fifth, drove him back over the Alps, and he set off in the train of Otto the Third, lamenting, says his biographer, that he should no more enjoy his beloved quiet in the mother of martyrs, the home of the Apostles, golden Rome. A few months later he died a martyr among the pagan Lithuanians of the Baltic[324]. Nearly four hundred years later, and nine hundred after the time of Alaric, Francis Petrarch writes thus to his friend John Colonna:-- 'Thinkest thou not that I long to see that city to which there has never been any like nor ever shall be; which even an enemy called a city of kings; of whose people it hath been written, "Great is the valour of the Roman people, great and terrible their name;" concerning whose unexampled glory and incomparable empire, which was, and is, and is to be, divine prophets have sung; where are the tombs of the apostles and martyrs and the bodies of so many thousands of the saints of Christ[325]?'