June 19, 1914] 



SCIENCE 



885 



It appears to be the general opinion that 

 each of the three stages brought in by the 

 three discoveries and inventions named 

 endured for a long period of time, perhaps 

 for something like one hundred thousand 

 years or longer. In all of these stages our 

 ancestors were yet in the savage state. 

 The advance to the higher state of barbar- 

 ism was brought about by the marvelous 

 discovery of a means of making pottery. 

 Man learned to fashion moist clay into a 

 useful shape and burn it into hardness so 

 that it would endure use. The vessels so 

 constructed afforded him a means of boil- 

 ing his meats and vegetables so that many 

 of them became highly palatable, whereas 

 they were almost or quite inedible when 

 merely roasted before a fire. 



Man, having advanced thus far, was still 

 in a very unsatisfactory state when viewed 

 from our present organization of commu- 

 nities with fixed abodes. He was neces- 

 sarily nomadic. If he settled down to live 

 permanently at a given place, then the 

 animals, upon which he depended so largely 

 for food would soon disappear from that 

 vicinity both because he destroyed them 

 and because he excited fear in them. But 

 after a time he found means for overcom- 

 ing this difficulty. Doubtless it had proved 

 profitable, to both the men and the dogs, 

 for the two to hunt together. Thus the 

 dog came to be domesticated. When the 

 idea that captive animals eould be of serv- 

 ice was clearly conceived, it was an easy 

 step to the domestication of the sheep, the 

 ox, the camel, the horse. Thus man came 

 to have a meat and milk supply readily 

 procurable at all seasons; in addition, he 

 had in the horse and the dog valuable as- 

 sistants in the chase. As his animals re- 

 quired pasture he came naturally to recog- 

 nize the value of an increased yield from 

 the soil. Thus, from being a herdsman, he 

 gradually developed into a husbandman. 



Then he came to have fixed abodes, and the 

 idea of nationality began to take definite 

 shape. 



At this stage of development man had no 

 very effective tools. Wood and bone and 

 chipped flints were the materials out of 

 which were made such as he had. Pres- 

 ently some one made the master discovery 

 of the art of smelting iron. From this time 

 forward man was equipped with tools 

 worthy his hand and his brain. 



This invention brought in the last of the 

 three periods of barbarism. Each probably 

 extended over many thousands of years. 

 During these periods man had leisure for 

 the development of his artistic sense; and 

 the way in which he used this leisure is 

 indicated by the remains of his art which 

 have endured to the present day — such as 

 the wonderful paintings found in numer- 

 ous caves in Europe. 



The age of civilization, properly so 

 called, was now brought in by an invention 

 comparable to that in connection with 

 which man emerged as man from his previ- 

 ous savage state. That early advancement, 

 you will recall, was associated with the 

 development of spoken language. The 

 new age of civilization was brought in by 

 the acquisition of written language. 



From this time forward progress has 

 been much more rapid than previously. 

 The first stage of civilization extended over 

 the period from the invention of writing to 

 the close of the so-called middle ages, when 

 a new stage was brought in by the inven- 

 tion almost simultaneously of gunpowder, 

 the mariner's compass, paper and the 

 printing press. Coupled with this was the 

 scientific discovery and the demonstration 

 by Copernicus that the sun and not the 

 earth is the center of our planetary system. 



These inventions and discoveries brought 

 about simultaneously three fundamental 

 revolutions in human thought and human 



