The faults of Brunelleschi's model are want of repose and absence of composition.

Abraham rushes in a frenzy of murderous agitation at his son, who writhes beneath the knife already at his throat.

The angel swoops from heaven with extended arms, reaching forth one hand to show the ram to Abraham, and clasping the patriarch's wrist with the other.

The ram meanwhile is scratching his nose with his near hind leg; one of the servants is taking a thorn from his foot, while the other fills a cup from the stream at which the ass is drinking.

Thus each figure has a separate uneasy action.