Having banished their rivals, the party in power for the time being remodeled the institutions of the republic to suit their own particular interest.

Meanwhile the opposition in exile fomented every element of discontent within the city, which this short-sighted policy was sure to foster.

Sudden revolutions were the result, attended in most cases by massacres consequent upon the victorious return of the outlaws.
To the action of these peccant humors--_umori_ is the word applied by the elder Florentine historians to the troubles attendant upon factions--must be added the jealousy of neighboring cities, the cupidity of intriguing princes, the partisanship of the Guelfs and Ghibellines, the treason and the egotism of mercenary generals, and the false foreign policy which led the Italians to rely for aid on France or Germany or Spain.

Little by little, under the prolonged action of these disturbing forces, each republic in turn became weaker, more confused in policy, more mistrustful of itself and its own citizens, more subdivided into petty but ineradicable factions, until at last it fell a prey either to some foreign potentate, or to the Church, or else to an ambitious family among its members.

The small scale of the Italian commonwealths, taken singly, favored rapid change, and gave an undue value to distinguished wealth or unscrupulous ability among the burghers.