524 THE POPULAR SCIENCE MONTHLY. 



invisible forms a man who had passed into an invisible state, or who 

 could become invisible when sought. 



Nothing approaching to the physical explanation of an echo can be 

 framed by the uncivilized man. What does he know about the reflec- 

 tion of sound-waves ? what, indeed, is known about the reflection of 

 sound-waves by the mass of our own people ? Were it not that the 

 spread of knowledge has modified the mode of thought throughout all 

 classes, producing eyerywhere a readiness to accept what we call natu- 

 ral interpretations, and to assume that there are natural interpretations 

 to occurrences not comprehended, there would even now be an ex- 

 planation of echoes as caused by unseen beings. 



That to the primitive mind they thus present themselves is shown 

 by facts. Southey, writing of the Abipones, says that " what became 

 of the Lokal " (spirit of the dead) " they knew not, but they fear it, and 

 believe that the echo was its voice." Concerning the Indians of Cu- 

 mana (Central America), Herrera tells us that they " believed the soul 

 to be immortal, that it did eat and drink in a plain where it resided, 

 and that the echo was its answer to him that spoke or called." And, 

 narrating his voyage down the Niger, Lander says that " from time 

 to time, as we came to a turn in the creek, the captain of the canoe 

 halloed to the fetich, and, where an echo was returned, half a glass of 

 rum and a piece of yam and fish were thrown into the water. When 

 asked why, he said, 'Did you not hear the fetich?' " 



Here, as before, I must ask the reader to ignore these special in- 

 terpretations, acceptance of which forestalls the argument. Attention 

 is now drawn to this evidence simply as confirming the inference that, 

 in the absence of physical explanation, an echo is conceived as the 

 voice of some one who avoids being seen. So that once more we have 

 duality implied of an invisible as well as a visible state. 



To a mind unfurnished with any ideas save those of its own gath- 

 ering, surrounding Nature thus presents multitudinous cases of seem- 

 ingly-arbitrary change now slight and slow, now gradual and great, 

 now sudden and extreme. In the sky and on the earth, things make 

 their appearance and disappear ; and there is nothing to show why 

 they do so. Here on the surface and there deeply embedded in the 

 ground are things that have been transmuted in substance changed 

 from flesh to stone, from wood to flint. Living bodies on all sides 

 exemplify metamorphosis in ways marvelous enough to the instructed, 

 and to the primitive man quite incomprehensible. And this protean 

 character which so many things around him exhibit, and which famil- 

 iarize him with the notion that there are two or more interchangeable 

 states of existence, is again impressed on him by such phenomena as 

 shadows, reflections, and echoes. 



Did we not thoughtlessly accept as innate the conceptions slowly 

 elaborated during civilization and acquired insensibly during our early 

 days, we should at once see that these ideas which the primitive man 



