8o PHYSICAL BASIS OF CIVILIZATION 



possibly be congruent or even proportionate to the 

 general properties, dimensions, special relations, or 

 forms of these. 



If they all had only length and breadth, no depth or 

 height, and were all located at the same distance from 

 the beholder, only then would this be possible. And 

 external things and conditions never are and never 

 can be that way ; for space has three dimensions. 



The sudden appearance of extraordinarily strong 

 light sometimes causes a nerve shock or a pain in the 

 eye. Intensely deep, large shadows may produce 

 a less acute but similar effect ; so may also certain 

 combinations of colors. But these shocks or pains 

 cannot yield knowledge of the special properties of 

 the things and conditions they are derived from. 



Only when the same external causes frequently 

 react on the senses of sight and touch simultane- 

 ously and if, in the manner explained in earlier para- 

 graphs of this chapter, the images on the retina 

 have by repetitions been organically connected with 

 the sensations of contact, which were provoked 

 simultaneously with them, only then can lights, 

 shadows, colors, by memory or suggestion, lead to 

 those complex states of consciousness, such as con- 

 ceptions, thoughts, etc., which are the forerunners 

 of knowledge. Therefore will the infant, in whose 

 organism the connections above mentioned have not 

 had time to become organically connected when 

 excited by vision, stretch out his hands to grasp the 

 moon. 



