The continual increase of Florentine commerce by land made the necessity of free access to the sea ever more pressing and indispensable. But to reach either Porto Pisano or Leghorn, the only ports convenient for their trade, they must necessarily traverse the republic of Pisa, their powerful neighbour and rival. For if the Florentines were masters of nearly the whole Tuscan trade by land, the Pisans were lords of the sea, and had no intention of allowing their realm to be snatched from them by so industrious and energetic a race as their competing neighbours. Accordingly the Pisans had only to demand heavy tolls for the passage of those neighbours' goods, and the Florentines were left with no remedy save recourse to arms. Hence the continual warfare and perpetual rivalry of the two republics. After the capture of Volterra by the Florentines in 1254, the threatening attitude of their victorious troops drove the Pisans to grant free passage to their merchandise, and in 1273, 1293, 1327, and 1329 similarly compelled them to adhere to the same terms. Pisa, however, never yielded the point with a good grace, but merely to avoid war, or in consequence of defeat. Meanwhile the Florentines were continually extending their trade to remoter parts of the East, and concluding fresh treaties there. This, while increasing their desire to command the sea, fanned the jealousy of Pisa to a fiercer flame. In Pagnini's work on "La Decima" we find an essay on the "Practise of Trade" ("Pratica della Mercatura"), written early in the fourteenth century by an agent of the Bardi firm, one Balducci Pegolotti. Next to Marco Polo's "Milione," this work is one of our most important sources of information regarding Italian travels and trading enterprises in the Levant, and furnishes specially minute details of Florentine traffic. From what Pegolotti tells us of his own doings, we may judge what was done by his fellow-citizens in general. In 1315 he succeeded in securing for them in Antwerp and Brabant similar franchises to those already enjoyed by the Genoese, Germans, and English. He afterwards went to the Levant, and found at Cyprus that the Bardi and Peruzzi alone shared the privilege granted to the Pisans of only paying 2 per cent. import and export duty; whereas all other Florentines had either to pay 4 per cent., or feign to be Pisans, a device exposing them to many spiteful reprisals from the latter, who treated them _worse than slaves or Jews_. These proceedings aroused Pegolotti's wrath, so that, although he was one of the Bardi firm, he made great and successful efforts to have the same privilege of franchise extended to the rest of the Florentines (1324). Thus, their common interests being promoted no less by the energy of individuals than by that of their government, these merchants continued to make advance in the East, and stir the Pisans to greater envy. In fact, the latter decided in 1343 to reduce the exemptions allowed on Florentine