open book above the saint contains one of the practical jokes for which Vasari says he was known. Most of the "text" is scribbles, but one line reads: "Where is Brother Martino? He went out. And where did he go? He is outside Porta al Prato", probably dialogue overheard from the Umiliati, the order who ran the church. Lightbown suggests that this shows Botticelli thought "the example of Jerome and Augustine likely to be thrown away on the Umiliati as he knew them". Sistine Chapel In 1481, Pope Sixtus IV summoned Botticelli and other prominent Florentine and Umbrian artists to fresco the walls of the newly completed Sistine Chapel. This large project was to be the main decoration of the chapel. Botticelli painted a series of portraits of popes. These works were called Temptation of Moses, Temptation of Christ, and Conturbation of the Laws of Moses. Most of the frescos remain but are greatly overshadowed and disrupted by Michelangelo's work of the next century, as some of the earlier frescos were destroyed to make room for his paintings. The Florentine contribution is thought to be part of a peace deal between Lorenzo Medici and the papacy. After Sixtus was implicated in the Pazzi conspiracy hostilities had escalated into excommunication for Lorenzo and other Florentine officials and a small "Pazzi War". The iconographic scheme was a pair of cycles, facing each other on the sides of the chapel, of the Life of Christ and the Life of Moses, together suggesting the supremacy of the Papacy. Botticelli's contribution included three of the original fourteen large scenes: the Temptations of Christ, Youth of Moses and Punishment of the Sons of Corah (or various other titles), as well as several of the imagined portraits of popes in the level above, and paintings of unknown subjects in the lunettes above, where Michelangelo's Sistine Chapel ceiling now is. He may have also done a fourth scene on the end wall opposite the altar, now destroyed. Each painter brought a team of assistants from his workshop, as the space to be covered was considerable; each of the main panels is some 3.5 by 5.7 metres, and the work was done in a few months. Vasari implies that Botticelli was given overall artistic charge of the project, but modern art historians think it more likely that Pietro Perugino, the first artist to be employed, was given this role,