2i 4 DEVELOPMENT AND PURPOSE CHAP. 



period that they began to take full effect. In the earlier 

 inventions, again, the wit of the * practical ' man was still 

 the principal agent, but more and more as development has 

 proceeded has this latest industrial phase come to deserve 

 the name of the stage of Applied Science, and of the 

 control of the underlying forces of nature. 



We may perhaps best succeed in fixing the leading char- 

 acteristics of these stages by considering the materials used 

 by man in each, the motor forces employed, and the 

 methods by which food is won. Thus in the first stage 

 the chief implements are adaptations of materials half 

 formed by nature for the use to which they are put the 

 chipping of flint, the pointing of bones, the scraping, cut- 

 ting and stitching of skins and so forth. For power man 

 relies on his own right arm, and for food he goes direct to 

 the products of nature. Beyond this he hardly advances 

 before the close of the Palaeolithic period. In the next 

 stage we may take the potter's art as typical. A wholly 

 formless material is shaped by man to his ends, and with 

 the shaping of the clay vessel we may compare the spinning 

 and weaving which transform fabrics into thread and thread 

 into cloth. Animal power is added to man's, and food is 

 obtained by the breeding of animals and the cultivation of 

 the soil in both cases by using not merely the products of 

 nature but the productive powers of nature. In the third 

 stage the materials are themselves in part artificial, though 

 their discovery is sporadic and empirical. The great 

 apparent forces of nature, wind and water, are brought into 

 use by mechanical appliances, and similar appliances enable 

 human and animal power to be transformed in kind and 

 direction. Agriculture begins to be intensive, natural 

 fertility is increased, its lack even is made good by manures, 

 and natural species are improved by breeding and grafting. 

 In the fourth stage substances may be disintegrated and 

 reconstructed from their elements. Molecular and ultra- 

 molecular forces vapour tension, electrical attraction and 

 repulsion, chemical affinity are brought within the compre- 

 hension and, finally, within the service of man. Chemistry, 

 bacteriology and the science of heredity are being applied 

 to the systematic production of the best forms of plant and 



