MENTAL AND SOCIAL EVOLUTION 125 



herd in the corral, and then came to the door, for 

 something to eat. After being fed, he took the sheep 

 out of the corral, and onto the range for feeding, 

 bringing them in each evening, watering them in the 

 river, and repeating this service each day, until the 

 sheep were found by the owners. Innumerable in- 

 stances might be given of equal intelligence in dogs. 



SLEEP. Even sleep, which is the period of rest, to 

 the functions of the nervous system, is caused by the 

 contraction of the blood vessels of the brain, and the 

 enlargement of the peripheral termination of the 

 circulatory system, thus lessening the activity of the 

 molecular motion which sustains psychic phenomena. 

 The resulting inactivity of the senses, is sleep. It is 

 often asserted that the mind, as some call the func- 

 tions of the nerve tissue, never sleeps. One proof of 

 this is the supposed mystery of dreams. The memory 

 images can only be true to the absent object, whose 

 representation constitutes the content of memory, when 

 the organs are fully awake and working normally. In 

 sleep, the vascular system is greatly modified. The 

 molecular motion of the brain depends on the constant 

 renewal of the physiological units, as they become 

 exhausted in the psychical process. But sleep is the 

 anemia of the brain. Hence dreams are always 

 abnormal presentations in the brain. Very few of 

 them have any sane cohesion, and can seldom be en- 

 tirely recalled. They are like half taken photographs, 

 when the plates are not properly prepared. The brain 

 centers lack in sleep the physical elements necessary 

 to a normal image. 



The objective thing, or rather nature as a whole, 

 especially the inorganic, is that to which the organism 

 has adjusted itself during its whole evolution. Psychic- 



