The Casentino is the valley of the Upper Arno, whose course from its source on Monte Falterona is sketched by the poet in those strangely bitter lines put into the mouth of Rinier da Calboli in Purgatory,[338] while its trickling tributary streams, bathing the verdant slopes, are vividly described in a single _terzina_ by poor parched Adamo in Hell— Li ruscelletti che de’ verdi colli Del Casentin discendon giuso in Arno Facendo i lor canali freddi e molli.[339] We are in the country of the famous Conti Guidi, that stalwart family who so successfully maintained their feudal sway amid an environment of burgher republicanism; the clan of strong men who, for more than four centuries at least, were masters of this fertile district which stretches from the slopes of Falterona southward to the walls of Arezzo—that city of “curs” from which Arno “turns aside its nose in scorn.”[340] The offspring of the romance[341] of Guido Vecchio and “la buona Gualdrada,”[342] this grim four-branched family—the Guidi of Porciano, of Romena, of Battifolle and of Dovandola—they have left their lasting mark upon the country. Three of their castles remain, castles in which Dante was harboured in the earlier years of his exile. Porciano—playfully referred to, surely, in the “brutti porci” of Riniero?[343]—and Romena both in picturesque ruin; Poppi (Arnolfo’s first draft, as it is said, for the similar Palazzo Vecchio at Florence) repaired throughout the centuries, since Count Francesco handed it over in 1440 to Neri Capponi, representative of the Florentine Republic. We are in the country of Campaldino, the battle where Dante fought, and Corso Donati and Vieri de’ Cerchi, soon to be leaders of opposing factions in their native town, performed prodigies of valour side by side: the battle where on St. Barnabas’ Day in 1289 the Guelf party decisively reversed the humiliation of twenty-nine years before, and that under the very walls of the Convent of Certomondo, founded by the Guidi two years after Montaperti, in thanksgiving for that bloody victory— Lo strazio e ’l grande scempio Che fece l’ Arbia colorata in rosso.[344] We are in the country of St. Francis of Assisi, Dante’s great religious ideal; for a morning’s drive or walk up the steep road from Bibbiena brings us right up to the foot of the “Rude crag betwixt Tiber and Arno”[345] which all Christendom reveres. In taking the old road over the Consuma Pass from Pontassieve, we are following in the tracks of the Florentine host as it marched forth in June, 1289. After much discussion as to the best route, as Villani and Dino Campagni tell us,[346] they wisely decided to take this steeper and more perilous but shorter path. A short way beyond Pontassieve they would have left the Val d’ Arno, to strike the river again but a few miles from its source. They left it flowing north towards Florence; they would find it again running southwards in the direction of Arezzo.