Running around the edge at the level of the fictive balustrade are pairs of philosophers in grisaille: Around the base of the ceiling are the nine Museum: Clio (History), Melpomene (Tragedy), Polyhymnia (Rhetoric), Calliope (Poetry), Urania (Astronomy), Thalia (Comedy), Euterpe (Music), Terpsichore (Dance) and Erato (hymns)

All these figures were originally accompanied by Apollo, who was inexplicably replaced in a later restoration by a libidinous faun.

As goddesses of the arts and sciences, and together with the philosophers above the lunettes, they sustain the history of the world, narrated on the ceiling, and also add lustre to the Spanish monarchy.