The discovery that the earth was round, not flat, that Ulysses had no idle dream when he dreamed that there was another continent beyond the pillars of Hercules, was a matter of unspeakable moment to trade. When we recollect that almost to the same date belong the discovery of a maritime route to the East Indies, and the invention of printing, we cannot but recognize that a power, not willing to move with the times, but painfully, obstinately clinging to its own ideas and images, had to be left behind. The very causes for which the Hansa had been founded, insecurity of roads, want of international justice, and other barbarous and intolerant conditions, no longer existed. The League itself had developed from a liberator into an oppressor. It no longer fitted with the changing conditions; it too must change or perish. In vain did it point to ancient charters, evoke "inviolable treaties" acquired at the point of the sword or by might of wealth. It had to learn that of these treaties, as indeed of treaties in general, must be said that which is sadly, but too truly said of human promises, that they are "like pie-crust, made to be broken." The spirit of revolution, or rather of change, was abroad. It made itself felt in manners, in institutions, in governments. The capture of Constantinople by the Turks contributed to the new development. By warning Europe of a new and menacing danger, it drew yet more closely together the different states which the Crusades had already put into relations with one another, and for which the feudal system formed a sort of common link. This same event turned the stream of sciences, letters, and arts towards Italy. On the other hand, the princes were finding out the means of diminishing the power of the feudal lords and nobles. The subjugation of the power of these vassals undermined little by little the feudal system, and allowed this worn-out institution to be replaced by institutions more in conformity with the needs of modern society. Various states, that had been unable to develope their forces, owing to the abuse of the feudal system, moved swiftly forward, now that they were free from restraint, and, having succeeded in centralizing their power desired to give it a firm and equal step in the march onwards. Meanwhile the forces that existed in the hands of the rulers were active enough to assure the tranquillity of the people, but it was always possible to turn them from their destination; war might arise any moment out of the very institutions that ought to secure the maintenance of peace. The people, recognizing this and fearing lest ambitious rulers should form projects of aggrandizement and conquest, had recourse to that policy which the Italian republics had already initiated and in which Florence took the lead.