The Prophets and Sibyls appear to be the last word of Michael Angelo in decorative painting, as Raphael knew, for he assimilated the teaching both in the beautiful figures of Sibyls at Santa Maria della Pace and the Prophet Isaiah of San Agostino.

The motives of the genii or angels, wise children whispering in the ears of the foretellers, seem to be inspired by the sculpture of Giovanni Pisano as seen in the pilasters of the pulpit of the Church of San Andrea at Pistoia.
It would be endless to try and tell all the thoughts and emotions, both literary and artistic, suggested by the contemplation of these figures and by the groups representing the Ancestors of Christ.

Suffice it to say, that all the thoughts that come into the minds of the beholders are as nothing compared to the thoughts that passed through the mind of the solitary artist composing and painting upon the high scaffolding of the quiet chapel.
The series of the Ancestors of Christ illustrate the life of a being upon this earth, from the terrible moment when the pregnant woman first feels the pangs of approaching labour, in the semicircle of the window (inscribed Roboam, Abias) to the lean and slippered pantaloon, who needs a stick to help him rise from his seat (over the window inscribed Salmon, Boaz, Obeth); there is the happy mother sleeping with her infant wrapped in swaddling-clothes (Salmon, Boaz, Obeth); and the old man playing with the children, (Eleazr, Matthew); the student attentively poring over his book regardless of the female figure, possibly Inspiration, speaking to him from the other side of the window (Naason).

These figures, the Ancestors of Christ, are more slightly painted than the rest of the vault.
They loom out of the darkness, caused by contrast to the light of the windows they surround, grow in and out of the background and have an atmospheric effect unequalled in fresco painting.

Those who walk from the Ponte Saint Angelo up the Borgo to the Vatican any morning early may see at the back of the dim recesses of the arched cellar-like shops such groups as these.