In spite of its complexity and scientific precision, the vault of the Sistine does not strike the mind as being artificial or worked out by calculation, but as being predestined to existence, inevitable, a cosmos instinct with vitality.
On the pendentives between the spaces of the windows, running up to the ends of each of the five lesser pictures, Michelangelo placed alternate prophets and sibyls upon firm projecting consoles.

Five sibyls and five prophets run along the side-walls of the chapel.

The end-walls sustain each of them a prophet.

These twelve figures are introduced as heralds and pioneers of Christ the Saviour, whose presence on the earth is demanded by the fall of man and the renewal of sin after the Deluge.

In the lunettes above the windows and the arched recesses or spandrels over them are depicted scenes setting forth the genealogy of Christ and of His Mother.