ON OUR PRESENT KNOWLEDGE OF THE ORIGIN OP MAN. 467 



the most violent opposition in an isolated department of neuro- 

 physiology, namely, that of psychology. The wonderful " soul of man " 

 was thought to be a peculiar "being," and it today seems to many 

 impossible that it should have been historically developed from the 

 "soul of the ape." But iu the first place the wonderful discoveries of 

 comparative anatomy during the last ten years inform us for the first 

 time that the minute as well as the gross structure of the brain of man 

 is the same as that of the anthropoid apes, the unimportant difference 

 in shape and size of single parts that exists between the two being less 

 than the corresponding difference between the anthropoid and the low- 

 est apes of the Old World, especially such as the baboons. Secondly, 

 comparative ontogeny teaches us that the very highly complex brain 

 of man has developed out of the same rudimentary form as that of all 

 other vertebrate animals — out of five cerebral vesicles of the embryo 

 that lie one 1 behind the other. The special way and method by which 

 the peculiar form of the primate brain is developed out of this extremely 

 simple rudiment is found to be exactly the same in man as in the 

 anthropoid apes. Thirdly, comparative physiology shows us by obser- 

 vation and experiment that the total functions of the brain, even con- 

 sciousness and the so-called higher mental faculties, together with reflex 

 acts, are in man preceded by the same physical and chemical phenomena 

 as in all other mammals. Fourthly and lastly, we learn through com- 

 parative pathology that all so-called "rueutal diseases" in man are 

 determined by material changes in the material of the brain, just as 

 they are in the nearest related mammals. 



An unprejudiced critical comparison confirms here also Huxley's 

 law: the psychological differences between man and the anthropoid 

 apes are less than the corresponding differences between the anthro- 

 poid and the lowest apes. And this physiological fact corresponds 

 exactly with the results of an anatomical examination of the differences 

 found in the structure of the cortex of the brain, the most important 

 "organ of the soul." The deep significance of this information will be 

 clearer to us when we consider the extraordinary differences in mental 

 capacity that exist within the human species itself. There we see, high 

 above, a Goethe and a Shakespeare, a Darwin and a Lamarck, a 

 Spinoza and an Aristotle, and then, far below, a Veddah and an Akkah, 

 a Bushman and a Patagonian. The enormous difference in mental 

 capacity between these highest and lowest representatives of the 

 human race is much greater than between the latter and the anthropoid 

 apes. 



Since, in spite of this, we find that the soul of man is to-day regarded 

 in the widest circles as an especial, "being" and as the most important 

 witness against the decried doctrine of the descent of man from apes, 

 we explain it on the one hand by the wretched condition of the so-called 

 "psychology," on the other by the widespread superstition concerning 

 the immortality of the soul. The science which to-day in most text- 



