POWELL] TECHNOLOGY . XXXI 



motives, although they can not exist apart. Every activity, 

 when performed, involves all the concomitant effects. The 

 world is concrete, but the method of consideration is often 

 abstract. 



Industries are classified as substantiation, construction, 

 mechanics, coramei'ce, and medicine. 



Substantiation 



Certain activities of welfare are fundamental thereto, because 

 they are necessary to life. We must breathe air, we must 

 drink water, we must eat food, we must seek shelter from the 

 elements^ and we must wear clothing In the pursuit of these 

 necessities of life human activities are emplu^'ed, even in the 

 primordial stage of savagery. Four of these necessary activi- 

 ties are pursued by the lower animals — they seek water, food, 

 and shelter for their young and sometimes for their compan- 

 ions — but artificial clothing is not worn by them. Activities 

 pursued for the welfare of self and others are industries. 



The natural kinds fundamentally necessary to man are 

 found by experience to be air, water, rocks, plants and 

 animals. 



Air is necessary at every minute of life, and it is so abun- 

 dant that man is not required to produce artificial air, though 

 as civilization advances he finds it necessarv to jjrovide for its 

 purity. 



Water also is abundant. Man does not find it necessary to 

 produce water from its elements, but he does find it necessary 

 to produce it at the place where it is needed and to provide 

 for its purity. 



Minerals are found to be useful to man primarily, jierhaps, 

 for slielter; soon they are found useful as tools, and he engages 

 in their production bv quarrying and raining. 



Plants are found to he useful to man as food in all its varie- 

 ties, as sap, leaves, bark, roots, seeds, and fruits. Plants are 

 also useful to man in pi'oviding shelter, and various parts of 

 the plant are used in the construction of houses by human 

 devices. Plants ai-e also found useful to man as fibers in 

 clothing. 



