PALAEONTOLOGY AND GEOLOGY 



cenna. This reference is worth quoting as, besides re- 

 peating the geologic theory of Theophrastus, Avi- 

 cenna attempts to explain the cause of fossils. He 

 says: "Rocks are formed from a viscous mud by the 

 heat of the sun or from water which coagulates a dry 

 and terrestrial virtue. Likewise, certain vegetables 

 and animals can be converted into stone by a certain 

 mineral and petrifying virtue." Thus the mysterious 

 term virtue entered into literature as a force of na- 

 ture and became the easy explanation, or rather one 

 should say the satisfying avoidance, of all incom- 

 prehensible problems. 



As might be expected, Duhem finds that that uni- 

 versal genius Leonardo da Vinci, who found time to 

 meditate upon and to adorn every phase of thought 

 and art, had made a persistent search for the origin 



"^ The word virtue has had a remarkable career. From its original 

 meaning of manly strength, or courage, it came to have a significance 

 of all the moral excellences. From our habit of personification of 

 the attributes of men, virtue gradually was looked upon as a spirit 

 residing in a man which caused him to act virtuously. So, when the 

 translators of the Bible sought for a term to express the miraculous 

 power of Jesus, they used this word as a synonym for the Greek 

 word, dunamis, which means power and is now the scientific term 

 for force, as in "dynamic" and "dynamo." This substitution occurs 

 in the passage : "Jesus, immediately knowing in himself that virtue 

 had gone out of him, turned him about." In the same way when 

 Albertus Magnus sought for a word to express the meaning of 

 Avicenna that some force exists in inert matter to change mud into 

 rock he at once turned to virtue. The custom spread until there was 

 a long category of virtues in matter which were the active prin- 

 ciples of heat, electricity, magnetism, etc. Then the moral and 

 physical principles were separated and physical forces were desig- 

 nated as subtile fluids; the next step was to dematerialize the fluids 

 into fields of force to explain the attraction of matter, electricity, 

 etc. At the present time, the final step in this remarkable chain has 

 taken place and the attributes of matter, — energy, heat, and elec- 

 tricity — have become metaphysical entities while matter itself, as 

 determined by inertia, has sunk into a state of innocuous lethargy. 



C 127 1 



