“Henricus ab Heeres (in his ‘Obs. Med.’) says that when he was a professor he used to rise in the night, open his desk, compose much, shut his desk, and again to bed. On his waking, he was conscious of nothing but the happy result of his composition. “The engineer Brindley even retired to bed for a _day or two_, when he was reflecting on a grand or scientific project. “I deny not that the darkness or stillness of night may have had some influence during this inspiration. I may also allow that some individuals compose best while they are walking, but this _peripatetic_ exertion is calculated itself to produce what we term determination of blood to the head. I have heard of a most remarkable instance of the power of position in influencing mental energy in a German student who was accustomed to study and compose with his head on the ground, and his feet elevated and resting against the wall. “And this is a fragment of a passage from Tissot, on the subject of monomania. “----‘Nous avons vu étudier dans cette académie, il n’y a pas long temps, un jeune homme de mérite, qui _s’étant mis dans la tête_ de découvrir la quadrature du cercle, est mort, fou, à l’Hôtel Dieu à Paris.’[135] “You will smile when I tell you that the tints of the landscape are brighter to our eyes if we _reverse the position of the head_.” Tissot, in the work to which reference has just been made, cites an instance in which position was taken advantage of to solve a problem in mathematics. A gentleman, remarkable for his accuracy in calculation, for a wager _lay down on a bed_ and wrought, by mere strength of memory, a question in geometrical progression, while another person, in another apartment, performed the same operation with pen and ink. When both had finished, the one who had worked mentally repeated his product, which amounted to sixteen figures, and, insisting that the other gentleman was wrong, desired him to read over his different products. On this being done he pointed out the place where the first mistake lay, and which had run through the whole. He paid very dearly, however, for gaining his wager, as for a considerable time he had a swimming in his head, pains in his eyes, and severe headaches upon attempting any mathematical labor. Sir Walter Scott has said somewhere, that the half hour _passed in bed_, after waking in the morning, was the part of the day during which he conceived his best thoughts. Dr. Forbes Winslow[136] makes some excellent remarks upon the relations existing between position and wakefulness. He says: