Del Sarto’s “Madonna of the Steps,” too fragile to travel from the Prado, appears here in the form of sketched details: images of piled drapery, of nude bodies (studio staff was no doubt recruited to pose), of detached feet and hands (including a tarantulalike set of fingers) and of a sweet child’s head, with another half-visible, like a mirage, behind it.
Source: wiktionary