In our dreams we seem to walk, talk, and perform various other actions, yet we do not actually do any of these things. As Cicero remarks, if it were required that we actually do all we dream of doing it would be necessary that every man be bound to his bed on going to sleep.

The failure of actual movement to accompany dreams should cause no wonder. We seem to move simply because we imagine that we move, and as long as we imagine that we move we are able to perform uninterruptedly in the dream. Normal sleep requires that actual movements be abeyant, and for this reason the motor centres are quiescent. If movement had to actually accompany the thought of such, sleep would be unre-freshing and dream life practically impossible. Again, under the same conditions, waking imagination would suffer. In our waking thoughts we often imagine that we are playing golf, tennis, etc., and yet we make no actual movement corresponding to our thoughts. We may say that in sleep we do Hot move actually because we do not will to move; we move in the imagination only.

It happens at times that the dreamer does make gross movements, as sleep-walking, somniloquy or sleep-talking. When this occurs the sleep deviates from the normal; the motor centres, in place of being quiescent, are awake and under the control of the dream. In waking life, intense interest in a subject, or absent-mindedness, often allows the imagination to cause response from the motor centres; for example, talking to one's self.

It happens, also, that we sometimes desire to move in the dream but are unable to do so. In these cases the dream usually occurs during light sleep, the motor centres being unduly asleep and the sensory centres unduly awake. This is also an unnatural state. We will again consider these abnormalities.