different ideas. But the theory of Strümpell and Wundt is incapable of instancing any motive which has control over the relation between the external stimulus and the dream idea which has been selected to interpret it, and therefore of explaining the "peculiar choice" which the stimuli "often enough make in the course of their reproductive activity" (Lipps, Grundtatsachen des Seelenlebens, p. 170). Other objections may be directed against the fundamental assumption of the whole theory of illusions—the assumption that during sleep the mind is not in a condition to recognise the real nature of the objective sensory stimuli. The old physiologist Burdach8 proves to us that the mind is quite capable even during sleep of interpreting correctly the sensory impressions which reach it, and of reacting in accordance with the correct interpretation. He establishes this by showing that it is possible to exempt certain impressions which seem important to the individuals, from the neglect of sleeping (nurse and child), and that one is more surely awakened by one's own name than by an indifferent auditory impression, all of which presupposes, of course, that the mind distinguishes among sensations, even in sleep (Chapter I., p. 41). Burdach infers from these observations that it is not an incapability of interpreting sensory stimuli in the sleeping state which must be assumed, but a lack of interest in them. The same arguments which Burdach used in 1830, later reappear unchanged in the works of Lipps in the year 1883, where they are employed for the purpose of attacking the theory of somatic stimuli. According to this the mind seems to be like the sleeper in the anecdote, who, upon being asked, "Are you asleep?" answers "No," and upon being again addressed with the words, "Then lend me ten florins," takes refuge in the excuse: "I am asleep."
The inadequacy of the theory of somatic dream stimuli may also be demonstrated in another manner. Observations show that I am not urged to dream by external stimulations, even if these stimulations appear in the dream as soon as, and in case that, I dream. In response to the tactile or pressure stimulus which I get while sleeping, various reactions are at my disposal. I can overlook it and discover only upon awakening that my leg has been uncovered or my arm under pressure; pathology shows the most numerous examples where power-
