208 ON THOUGHT IN MEDICINE. 



we assign the name of mammals to those animals which > 

 when young, are suckled by their mothers, we can 

 assert further, in reference to them, that they are all 

 warm-blooded animals, born alive, that they have a 

 spinal column but no quadrate bone, breathe through 

 lungs, have separate divisions of the heart, &c. Hence 

 the fact, that in the speech of an intelligent observing 

 people a certain class of things are included in one 

 name, indicates that these things or cases fall under a 

 common natural relationship ; by this alone a host of 

 experiences are transmitted from preceding generations 

 without this appearing to be the case. 



The adult, moreover, when he begins to reflect upon 

 the origin of his knowledge, is in possession of a huge 

 mass of every-day experiences, which in great part 

 reach back to the obscurity of his first childhood. 

 Everything individual has long been forgotten, but 

 the similar traces which the daily repetition of similar 

 cases has left in his memory have deeply engraved 

 themselves. And since only that which is in con- 

 formity with law is always repeated with regularity, 

 these deeply impressed remains of all previous con- 

 ceptions are just the conceptions of what is conform- 

 able to law in the things and processes. 



Thus man, when he begins to reflect, finds that he 

 possesses a wide range of acquirements of which he 

 knows not whence they came, which he has possessed 



