136 SCIENCE AND THE HUMAN MIND 



George Ernest Stahl (1660-1734), physician to the 

 King of Prussia, developed the idea of a volatile 

 " principle " to explain the phenomena of combus- 

 tion. When bodies were burnt something apparently 

 escaped, and this something Stahl named phlogiston, 

 the " principle of fire/' Although this view regarded 

 burning as a loss of substance, and was thus in con- 

 tradiction to facts known to Boyle, who had shown 

 that metals increased in weight on burning, it was so 

 powerfully advocated, and expressed so well the ideas 

 of the age, that it gained general acceptance, and 

 dominated the chemical ideas of the whole eighteenth 

 century. Stahl also opposed the somewhat crude, 

 and at all events premature, materialistic views which 

 were beginning once more to appear in physiology. 

 He held that the chemical changes in living bodies, 

 though carried on in accordance with those produced 

 in the laboratory, were directed and governed by 

 the "sensitive soul" described by Aristotle a view 

 which lived long under the name of vital force, and 

 in another form is perhaps once more coming to be 

 thought necessary to explain the phenomena of the 

 living organism as a complex adaptive synthesis of 

 matter and energy. 



During the seventeenth and eighteenth centuries 

 the systematic exploration of the world began to take 

 Voyages of &$ place in the organised pursuit of know- 

 Discovery, ledge. If the explorers of this period 

 cannot claim for their voyages the romance associated 

 with the pioneers of discovery in the fifteenth and 

 sixteenth centuries, pioneers who first revealed the 

 existence of the earth as we now know it and mapped 



