Florentine commerce and industry undoubtedly increased during the rule of Countess Matilda. This has been proved by the patent of 1081, and the first wars undertaken by the Florentines in the interest of their trade afford sure confirmation of the fact. Were we to exclude trade associations from the conditions of the period, we should have to admit the existence, at that day, of the modern workman, isolated and independent: a decided impossibility in the Middle Ages. Those were times in which every trade was exercised by distinct groups of families, and handed down by them as a tradition from father to son. Frequently, even offices of the State were the monopoly of certain families. It was from a society split into groups and castes that the Commune eventually developed the modern State, but in old times the very idea of the latter was unconceived. It is absurd to suppose--though a few writers accept the notion--that the guilds only began when they had regular statutes. These statutes only formulated what had already existed for some time, and undoubtedly in Florence everything conduces to the belief that the associations of the trades and of the towers, though still embryonic, must have preceded the formation of the Commune evolved in their midst. IV. For on all sides, if in diverse modes, we perceive that a long period of incubation was needed to form the Commune, which naturally owed its birth to pre-existing elements. The celebrated agreement or _concordia_ made at Pisa by Bishop Daiberto, about 1090, or even, perhaps, a year or so earlier,[98] shows that the nobles were organised and waging fierce war against one another from their towers. The bishop induced them to partly demolish these towers, and solemnly vow never to carry them above the height of thirty-six braccia (about one hundred feet), as previously decreed by the patent of Henry IV. in 1081.[99] And the agreement proceeded to set forth that any man believing his houses to have been unjustly damaged was to bear his complaint _ad commune Colloquium Civitatis_; nor could the dwelling of the offender be demolished without the general consent of the citizens.[100] [Illustration: MOUTH OF ROMAN FURNACE, _Discovered beneath the Mercato Vecchio._] [Illustration: CALIDARIUM. _Ibid._ [_To face page 96._]