ONTOGENY AND PIIYLOGENY. 23 



the Amphibia, Beaked Animals {Ornitho stoma), Pouched 

 Animals, or Marsupials, and Semi-apes {Prosimioi), until the 

 highly organized form is reached which distinguishes the 

 Apes from all other Vertebrates, and which finally attains 

 its highest development in the human brain. But step by 

 step with this progressive evolution of the form of the 

 brain, the evolution of its peculiar function, the psychical 

 activities, moves on hand in hand, and it is therefore the 

 history of the evolution of the central nervous system which 

 for the first time enables us to understand the origin of life 

 of the human mind from natural causes, and the gradual 

 historic development of the psychic activities of man. It is 

 impossible without the aid of Ontogeny to perceive how 

 these highest and most brilliant functions of the animal 

 organism have been historically developed. In a word, the 

 history of the evolution of the spinal marrow and the brain 

 of the human embryo at the same time directly leads us 

 to understand the Phylogeny of the human mind, that most 

 sublime activity of life which in the developed human being 

 we are accustomed to regard as something wonderful and 

 supernatural. 



There is no doubt that this special result of the study 

 of the history of evolution is among the greatest and most 

 important. Happily, our knowledge of the Ontogeny of the 

 central nervous system of Man is so satisfactory, and agrees 

 so perfectly with the supplementary results of Comparative 

 Anatomy and Physiology, that it affords us a perfectly 

 clear insight into one of the highest problems of philosophy, 

 '^namely, the Phylogeny of the psyche, tlie mind, or the 

 history of the ancestral lineage of Man's psychic activities, 

 and leads us into the only path by which we shall ever be 

 able to solve this the highest of all problems. 



