'Twice or thrice a week you must anoint your body thoroughly with the manna of cassia; and every night, before going to bed, you must place over your heart a plaster, composed of a certain quantity (or, rather, uncertain, for definite and precise proportions are never particularized) of Oriental saffron, red rose-leaves, sandal-wood, aloes, and amber, liquefied in oil of roses and the best white wax. During the day this must be kept in a leaden casket. You must next pen up in a court, where the water is sweet and the air pure, sixteen chickens, if you are of a sanguine temperament; twenty-five, if phlegmatic; and thirty, if melancholic. Of these you are to eat one a day, after they have been fattened in such a manner as to have absorbed into their system the qualities which will ensure your longevity; for which purpose they are first to be kept without food until almost starved, and then gorged with a broth of serpents and vinegar, thickened with wheat and beans, for at least two months. When they are served at your table you will drink a moderate quantity of white wine or claret to assist digestion.'
Among the alchemists must be included _Pietro d'Apono_. He was an eminent physician; but, being accused of heresy, was thrown into prison and died there. His ecclesiastical persecutors, however, burned his bones rather than be entirely disappointed of their _auto da fé_. Like most of the mediæval physicians, he indulged in alchemical and astrological speculations; but they proved to Pietro d'Apono neither pleasurable nor profitable. It was reputed of him that he had summoned a number of evil spirits; and, on their obeying his call, had shut them up in seven crystal vases, where he detained them until he had occasion for their services. In his selection of them he seems to have displayed a commendably catholic taste and love of knowledge; for one was an expert in poetry, another in painting, a third in philosophy, a fourth in physic, a fifth in astrology, a sixth in music, and a seventh in alchemy. So that when he required instruction in either of these arts or sciences, he simply tapped the proper crystal vase and laid on a spirit.
The story seems to be a fanciful allusion to the various acquirements of Pietro d'Apono; but if intended at first as a kind of allegory, it came in due time to be accepted literally.