If the doctor had turned to contemporary authorities on insomnia, he would have found little of use. Sleep, even now a mystery in many ways to science and medicine, was utterly obscure to the doctors of his time, who were still struggling to understand what went on in plain sight in the day. Indeed, the unsleeping doctor would have had to go all the way back to Galen, the ancient Roman physician whose teachings had dominated medicine until Galileo had challenged him a century before. Galen had learned most of what he knew about sleep from Aristotle, who had pronounced condently on the question (as he had on most scientific issues). "All things that have a natural function," he wrote authoritatively in On Sleep and Dreams, "must, whenever they exceed the time for which they can do a certain thing, lose their capacity and cease from doing it, e.g., the eyes from seeing. Necessarily, everything that wakes must be capable of sleeping. For it is unable to be active at all times." Aristotle proposed that sleep was a byproduct of eating. After a person had a big meal the warm fumes from the process of digestion entered the veins, thence to the brain, and thither to the heart, the seat of consciousness, where their cooling brought about sleep. Galen, writing five centuries after him, corrected Aristotle -- the warm meal went directly to the brain, where it plugged the pores by which sensations entered and exited.
It is unlikely the Venetian doctor took either Galen or Aristotle seriously. Both would have seemed speculative to him when compared to the certainties of the Acquapendente. Still, back in Venice now, to be on the safe side, he might have ordered his cook to produce bigger meals -- roast fowls and hams and sausages from the Adriatic doused in the heavy French sauces that were newly in style. If so, the results would have confirmed his skepticism about the learnedness of anyone who had not gone to Padua. He would have sat awake in a chair, his stomach distended, waiting for the meal to warm his head. To help the process along he would have had plenty of wine, as well -- wine was particularly recommended for insomnia -- and then sat up through the night until the sun rose over the Lido.