ANIMAL CONSCIOUSNESS 17 



power of abstract thought, but every form of psychic 

 life whatever, and reduced the lower form to a machine, 

 which automatically reacted upon external stimuli. This 

 daring view, however, prevailed for only a comparatively 

 short period; but owing to the opposition which it 

 aroused, it gave a tremendous impetus to the study of 

 animal consciousness. Most of the great philosophers 

 following Descartes, such as Locke, Leibniz, Kant, and 

 Schopenhauer, however greatly they may have differed 

 in other points, in this one returned to the Aristotelian 

 point of view. 



A third belief avers that animal and human conscious- 

 ness do not differ in essentials, but only in degree. This 

 conclusion is regularly arrived at by those who regard 

 so-called abstract thought itself, as simply a play of in- 

 dividual sensations and sensation-images, as did the 

 French and British associationists (Condillac and the 

 Mills). The superiority of man accordingly consisted 

 in his ability to form more intricate ideational complexes. 

 Again, this conception of the essential similarity of the 

 human and the animal psyche has also always been ar- 

 rived at by the materialists (from Epicurus to C. Vogt 

 and Biichner) who impute reason to the animal form as 

 well as to man. The same position is, furthermore, taken 

 by the evolutionists, including those who do not subscribe 

 to the doctrines of materialism. It has almost become 

 dogma with them that there exists an unbroken chain 

 of psychic life from the lowest protozoa to man. 

 Haeckel, preeminently, though not always convincingly, 

 sought to establish such a graded series and thus to 

 bridge the chasm between the human and the animal 

 consciousness. 



Two tendencies, therefore, are discernible in animal 



