To a man like Domenico Neroni, devoid of classical learning and accustomed to struggling with anatomy and perspective, the problem of ancient art was not settled by the fact of its antiquity. He had gone once more to Rome on purpose to see as many old marbles as possible, and he brought to their study the feverish curiosity with which in former years he had flayed and cut up corpses and spent his nights in calculations of perspective. To such a mind, where modern scientific methods were arising among mediæval habits of allegory and mysticism, the statues and reliefs which he was perpetually analysing became a sort of subsidiary nature, whose riddles might be read by other means than mere investigation; for do not the forces of Nature, its elemental spirits, give obedience to wonderful words and potent combinations of numbers? Certain significant facts had flashed across his mind in his studies of that almost abstract, nay, almost cabalistic thing, the science of bodily proportions. It was plain that the mystery of antique beauty--the ancient symmetry, _symmetria prisca_ as a humanist designs it in his epitaph for Leonardo da Vinci--was but a matter of numbers. For a man's length, if he stand with outstretched arms, is the same from finger tip to finger tip as his length when erect from head to feet, namely, eight times the length of his head. Now eight heads, if divided into halves, give four as the measure of throat and thorax; and four heads to the length of the leg from the acetabulum to the heel, divided themselves into two heads going to the thigh and two heads to the shank; while in the cross measurement two heads equal the breadth of the chest, and three measure the length from the shoulder to the middle finger. These measures--a mere rough rule of thumb in our eyes--contained to this mediæval mind the promise of some great mystery. To him, accustomed to hear all the occurrences of Nature, and all human concerns referred to astrological calculations, and conceiving the universe as governed by spirits--in shape, perhaps, like the Primum Mobile, the Mercurius and Jupiter of Mantegna's playing cards, crowned with stars and poised upon globes--it was as if the divining rod were turning pertinaciously to one spot in the earth, where, had he but the necessary tools, he must strike upon veins of the purest gold, or cause water to spirt high in the air. This number _eight_, and the pertinacity of its recurrence, puzzled him intensely. It seemed to point so clearly, much as in music the sensitive seventh points to the tonic, to a sort of resolution on the number nine. And if only nine could be established, it would seem to explain so much.... For five being man's numeral in creation (and is not the measurement of his face also _five eyes_?), it makes, when added to four, the number of the material elements over which he dominates, _nine_, which would thus represent the supremacy or perfection of man.