Dr. Handfield Jones[132] relates a case in which the influence of position was strongly marked. “A gentleman aged twenty-four, after considerable mental strain, experienced the following symptoms: He was thoroughly weary and drowsy at the close of the day, and felt, as well he might, the need of nature’s restorer; scarcely, however, had he laid down his head, when the cerebral arteries began to throb forcibly, and soon all inclination for sleep was banished, and for hours he lay wide awake, but deadly weary. The _causa mali_ here was evidently deficient tonicity in the cerebral arteries, or more exactly paresis of their vasa motor nerves. As the arteries relaxed they admitted an undue flow of blood to the brain, which goaded the weary tissue to abnormal action.” De Boismont[133] refers to a case, on the authority of M. Moreau, in which an individual was able to obtain hallucinations of sight by inclining his head a little forward. By this movement the return of blood from the head was impeded, and thus there was an exaltation of certain of the cerebral functions. Wakefulness is nothing more than an exaggeration of the normal functions of the brain. For this organ to act with vigor, an increased flow of blood is necessary. If this flow is continued, without proper periods of repose, a state of erethism and insomnia is produced. Instances have been recorded in which persons have found it necessary to assume the recumbent position whenever they had any severe mental labor to perform. The following extract, bearing upon this point, from a work[134] already quoted, is interesting: “The posture of supination will unavoidably induce that increased flow of blood to the brain which, under certain states of this fluid, is so essential to the production of brilliant waking thoughts; and are indeed attained so often by another mode--the swallowing of opium. “A gentleman of high attainment was constantly haunted by a specter when he retired to rest, which seemed to attempt his life. When he raised himself in bed _the phantom vanished, but reappeared_ as he resumed the recumbent position. “Some persons always retire to bed when they wish to think; and it is well known that Pope was often wont to ring for pens, ink, and paper in the night, at Lord Bolingbroke’s, that he might record, ere it was lost, that most sublime or fanciful poesy which flashed through his mind as he lay in bed. Such, also, was the propensity of Margaret, Duchess of Newcastle, who (according to Cibber, or rather Shiel, the _real_ author of the ‘Lives of the Poets’) kept a great many young ladies about her person, who occasionally wrote what she dictated. Some of them slept in a room contiguous to that in which her grace lay, and were ready, at the call of her bell, to rise any hour of the night to write down her conceptions, lest they should escape her memory.