The trial-pieces prepared by Brunelleschi and Ghiberti are now preserved in the Bargello.[81] Their subject is the "Sacrifice of Isaac;" and a comparison of the two leaves no doubt of Ghiberti's superiority. 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. Those critics who contend that the unrest of sixteenth-century sculpture was due to changes in artistic and religious feeling wrought by the Renaissance, would do well to examine this plate, and see how much account must be taken of the artist's temperament in forming their opinion. Brunelleschi adhered to the style and taste of the fifteenth century at its commencement; but the too fervid quality of his character impaired his work as a sculptor. Ghiberti, on the other hand, translated the calm of his harmonious nature into his composition. The angel leans from heaven and points to the ram, which is seated quietly and out of sight of the main actors. Isaac kneels in the attitude of a submissive victim, though his head is turned aside, as if attracted by the rush of pinions through the air; while Abraham has but just lifted his hand, and the sacrifice is only suggested as a possibility by the naked knife. The two servants are grouped below in conversation, one on each side of the browsing ass. This power of telling a story plainly, but without dramatic vehemence; of eliminating the painful details of the subject, and combining its chief motives into one agreeable whole, gave peculiar charm to Ghiberti's manner. It marked him as an artist distinguished by good taste.