Such familiarity with nude form was not easily attained in the fifteenth century. Mediæval civilisation gave no opportunities for seeing naked or half-naked people moving freely as in the antique palæstra; and there had yet been discovered too few antique marbles for the empiric knowledge of ancient sculptors to be empirically inherited by modern ones. Observation of the hired model, utterly insufficient in itself, required to be supplemented by a thorough science of the body's mechanism. But physiology and surgery were still in their infancy; and artists could not, as they could after the teachings of Vesalius, Fallopius, and Cesalpinus, avail themselves of the science accumulated for medical purposes. Verrocchio and the Pollaiolos most certainly, and Donatello almost without a doubt, practised dissection as a part of their business, as Michelangelo, with the advantage of twenty years of their researches behind him, practised it passionately in his turn. Of all the men of his day, Domenico Neroni, however, was the most fervent anatomist. He ran every risk of contagion and of punishment in order to procure corpses from the hospital and the gibbet. He undermined his constitution by breathing and handling corruption, and when his friends implored him to spare his health, he would answer, although unable to touch food for sickness, by paraphrasing the famous words of Paolo Uccello, and exclaiming from among his grisly and abominable properties, "Ah! how sweet a thing is not anatomy!"