It would be doing Signorelli injustice at Orvieto to study only these great panels.  The details with which he has filled all the vacant spaces above the chapel stalls and round the doorway, throw new light upon his power.  The ostensible motive for this elaborate ornamentation is contained in the portraits of six poets, who are probably Homer, Virgil, Lucan, Horace, Ovid, and Dante, il sesto tra cotanto senno.[211] But the portraits themselves, though vigorously conceived and remarkable for bold foreshortening, are the least part of the whole design.  Its originality consists in the arabesques, medallions, and chiaroscuro bas-reliefs, where the human form, treated as absolutely plastic, supplies the sole decorative element.  The pilasters by the doorway, for example, are composed, after the usual type of Italian grotteschi, in imitation of antique candelabra, with numerous stages for the exhibition of the artist’s fancies.  Unlike the work of Raphael in the Loggie, these pilasters of Signorelli show no birds or beasts, no flowers or foliage, fruits or fauns, no masks or sphinxes.  They are crowded with naked men—­drinking, dancing, leaning forward, twisting themselves into strange attitudes, and adapting their bodies to the several degrees of the framework.  The same may be said of the arabesques around the portraits of the poets, where men, women, and children, some complete, some ending in foliage or in fish-tails, are lavished with a wild and terrible profusion.  Hippogriffs and centaurs, sirens and dolphins, are here used as adjuncts to humanity.  Amid this fantastic labyrinth of twisted forms we find medallions painted in chiaroscuro with subjects taken chiefly from Ovidian and Dantesque mythology.  Here every attitude of men in combat and in motion has been studied from the nude, and multitudes of figures draped and undraped are compressed into the briefest compass.  All but the human form is sternly eliminated; and the body itself is treated with a mastery and a boldness that prove Signorelli to have held its varied capabilities firmly in his brain.  He could not have worked out all those postures from the living model.  He played freely with his immense stores of knowledge; but his play was the pastime of a Prometheus.  Each pose, however hazardous, carries conviction with it of sincerity and truth; the life and liberty of nature reign throughout.  From the whole maze of interlaced and wrestling figures the terrible nature of the artist’s genius shines forth.  They are almost all strong men in the prime or past the prime of life, chosen for their salient display of vital structure.  Signorelli was the first, and, with the exception of Michael Angelo, the last painter thus to use the body, without sentiment, without voluptuousness, without any second intention whatsoever, as the supreme decorative principle.  In his absolute sincerity he made, as it were, a parade of hard and rugged types, scorning to introduce an element of beauty, whether sensuous or ideal, that should distract him from the study of the body in and for itself.  This distinguishes him in the arabesques at Orvieto alike from Mantegna and Michael Angelo, from Correggio and Raphael, from Titian and Paolo Veronese.