One picture in Stanza IV. (20) is unique among Sano's works, and may be described as a mystical treatment of contemporary history. Pope Calixtus III. is enthroned in full pontifical robes, his cope being buckled with the Borgia arms, while below appears Siena with the Tower of the Palazzo and the Campanile of the Duomo; mules are being driven into the city, laden with sacks of grain marked with the _balzana_, the muleteer being armed and looking round in fear to see if he is pursued. In the clouds the Madonna appears, to commend her city to the Holy Father, a scroll bearing her words: "O worthy Pastor to my Christian people, to thee henceforth do I render the care of Siena; to her let all thy kindly feeling turn." And we have his answer: "Virgin Mother, dear Consort to God, if thy Calixtus is worthy of so great a gift, nought save death shall sever me from Siena." Though somewhat hastily painted, and though the character of Calixtus is hardly more realised than in the case of Giotto's popes, the historical interest of the picture, which was executed for the Palazzo Pubblico, is considerable. In 1455, when Piccinino the great condottiere--in secret understanding with Giberto da Correggio, the commander of the Sienese forces, and with Ghino di Pietro Bellanti and other traitors within the walls--was preparing to make war upon the Republic, Calixtus (Alfonso Borgia), then newly-elected Pope, took Siena under his protection and sent the ecclesiastical forces to its support. He urged the Sienese to prosecute the war to the bitter end, declared that their cause was his own. "We shall maintain inviolate your own and the common peace and quiet of all Italy," he said to the Captain of the People and the Priors of the Commune in a bull dated August 14th, 1455, "even to the shedding of our own blood, if needs be." "You have a Pope," wrote Enea Silvio Piccolomini (who was not yet Cardinal), a few days later to the Balìa, "most affectionate towards [Illustration: _Madonna and Child._ _Detail from Duccio's Altarpiece._] your Republic, as you perceive; know how to take advantage of it, for his courage is as great as his charity, nor has he anything at heart save justice."[64] When the Balìa wanted to compromise and make peace, Calixtus would not hear of it, but sent abundant grain and provisions into the hungry city. This is the situation represented in the picture, which may confidently be dated 1455; but a comparison with the Pope's medals shows that Sano has hardly done justice to the rather striking features of the first Pope of the House of Borgia.