Attention, therefore, presupposes strength of will, and this, again, is the property only of a normally constituted and unexhausted brain. In the degenerate, whose brain and nervous system are characterized by hereditary malformations or irregularities; in the hysterical, whom we have learnt to regard as victims of exhaustion, the will is entirely lacking, is possessed only in a small degree. The consequence of weakness or want of will is incapacity of attention. Alexander Starr[77] published twenty-three cases of lesions, or diseases of the convolutions of the brain, in which ‘it was impossible for the patients to fix their attention’; and Ribot[78] remarks: ‘A man who is tired after a long walk, a convalescent who has undergone a severe illness--in a word, all weakened persons are incapable of attention.... Inability to be attentive accompanies all forms of exhaustion.’ Untended and unrestrained by attention, the brain activity of the degenerate and hysterical is capricious, and without aim or purpose. Through the unrestricted play of association representations are called into consciousness, and are free to run riot there. They are aroused and extinguished automatically; and the will does not interfere to strengthen or to suppress them. Representations mutually alien or mutually exclusive appear continuously. The fact that they are retained in consciousness simultaneously, and at about the same intensity, combines them (in conformity with the laws of conscious activity) into a thought which is necessarily absurd, and cannot express the true relations of phenomena.