The Sacrifice of Isaac is an absolute masterpiece of Renaissance sculpture, created in 1421 by Donatello and Nanni di Bartolo. The original location was on Giotto’s Bell Tower, in the third order of the east side, second niche from the right.

This was the first monumental group carved in the Renaissance consisting of two figures sculpted in the round and from a single block of marble; the figure of Isaac is also the first example of a life-size nude since ancient times. It is also the first time in sculpture that a third figure (the angel) is only alluded to and not represented, inaugurating a new relationship between form and space, figure and imagination.

The iconographic subject is taken from a famous biblical episode (Genesis 22.1-18): the patriarch Abraham responds to the call of God who, demanding proof of fidelity, has ordered Abraham to sacrifice Isaac, his only son. The sacrifice would not be consumed, since Abraham's hand was instead stopped by an angel sent by God.

In the work we see Abraham brandishing the sacrificial knife, while Isaac, kneeling at his father's feet, on the bundle of wood for the sacrifice, awaits his destiny, aware that he is God's chosen victim. Abraham is caught in the moment in which he suddenly turns upwards, at the call of the angel who orders him not to kill the child. The account of this sacrifice by a father of his only-begotten son was read by interpreters of the scriptures in the light of the New Testament, as a prefiguration of Christ's sacrifice.

The genius of Donatello managed to give the marble all the dramatic tension of the event: Abraham suddenly twists upwards and his face, of a meek and righteous old man, is overwhelmed by anguish. The fury of the rotation of his head is contrasted by the gesture of his left hand which - having heard the order - already loosens his grip on the knife. The energy emanating from the figure of the elderly Abraham is counterbalanced by the static and compliant pose of the child at his feet, depicted with the beauty of an ancient Greek statue.