It was not necessary for every guildsman to practise the art or engage in the business to which his guild was devoted, and we are not required to imagine Dante as having anything to do with medicine or with the spices and precious stones in which the apothecaries traded. The guilds were political as much as industrial associations, and of the public duties of his membership he took his full share. The constitution of the Republic, jealously careful to limit the power of the individual citizen, provided that the two chief executive officers, the Podesta and the Captain of the People, should always be foreigners. They held office only for six months. To each of them was assigned a numerous Council, and before a law could be abrogated or a new one passed it needed the approval of both these Councils, as well as that of the Priors, and of the heads of the principal guilds. The Priors were six in number, one for each district of the city. With them lay the administration in general of the laws, and the conduct of foreign affairs. Their office was elective, and held for two months.[74] Of one or other of the Councils Dante is known to have been a member in 1295, 1296, 1300, and 1301.[75] In 1299 he is found engaged on a political mission to the little hill-city of San Gemigniano, where in the town-house they still show the pulpit from which he addressed the local senate.[76] From the middle of June till the middle of August 1300 he served as one of the Priors.[77] At the time when Dante entered on this office, Florence was distracted by the feud of Blacks and Whites, names borrowed from the factions of Pistoia, but fated to become best known from their use in the city which adopted them. The strength of the Blacks lay in the nobles whom the Ordinances of Justice had been designed to depress; both such of them as had retained their standing as magnates, and such as, under the new law, had unwillingly entered the ranks of the citizens. Already they had succeeded in driving into exile Giano della Bella,[78] the chief author of the Ordinances; and their efforts--and those of the citizens who, fearing the growing power of the lesser guilds, were in sympathy with them--were steadily directed to upset the reforms. An obvious means to this end was to lower in popular esteem the public men whose policy it was to govern firmly on the new lines. The leader of the discontented party was Corso Donati, a man of small fortune, but of high birth; of splendid personal appearance, open-handed, and of popular manners. He and they who went with him affected a violent Guelfism, their chance of recovering the control of domestic affairs being the better the more they could frighten the Florentines with threats of evils like those incurred by the Aretines and Pisans from Ghibeline oppression. It may be imagined what meaning the cry of Ghibeline possessed in days when there was still a class of beggars in Florence--men of good names--whose eyes