Certainly the florin, or _zechin_, as it was called later, is worth about twelve Italian _lire_. But the difference in the value of gold remains involved in uncertainty. Besides, when old writers reckon by _lire_, it is needful to remember that these coins varied in value; that it is impossible to make even an approximative calculation without knowing the exact date referred to. Returning to the Guild of Changers, we must again insist on the point that, in addition to the extended commercial relations, the wise measures enforced by the Republic and the singular activity of the citizens, the rapid prosperity of the Florentine bankers was also greatly enhanced by their nearness to Rome. The revenues of the Holy See and of its prelates in all parts of Christendom were all poured into the Eternal City. There gathered the spiritual lords, bishops, and cardinals, holding rich benefices in the East or the West; thither from all the remotest ends of the known world believers sent sums of "St. Peter's pence," together with the costly offerings suited to a period of religious faith and fanaticism. The keen-witted Florentines quickly recognised the advantage of becoming bankers to the Pope; for thus the largest floating capital in the world would have to pass through their hands. So, from the first, they used the most persistent efforts to obtain that position. If we find them clinging to the Guelph cause through all changes of time and circumstance, and preserving the name of Guelphs, even when the term had lost all meaning, we must attribute no little weight to commercial as well as to political motives. Placed in the centre of Italy, and not far from Rome, they had to struggle chiefly against the Siennese, who were still nearer to the Eternal City. For this reason we soon find them engaged in warfare and jealous strife with Sienna, the which republic was subsequently worsted, not only in fight, but also by the wider-stretching enterprise of Florentine commerce. It is proved by the correspondence of Gregory IX. that even in 1233 the Tuscans were forwarding remittances to the Pope from various parts of the world; and gradually the monopoly of this business became more exclusively concentrated in Florentine hands. When the Pontifical Seat was transferred from Rome to Avignon (1305), and on its restoration later to Rome again, there occurred, twice at least, an enormous displacement of interest, a great movement of capital, and a necessity for large remittances in cash; and, according to the best authorities, this was the favourable moment when the Florentine contractors of the Papal revenues were enabled to become the principal bankers of Rome. From that time their fortune was assured, the greatest banking business in Europe passed through their hands, and they rose to so high a repute, that all sought their help and advice on matters of finance.