24 ARISTOTLE'S METHOD. 



many additional observations in order to test the results at 

 which he arrived. This want of appreciation of the value 

 of constant verification of results is evident in many parts of 

 his works. A simple experiment, such as Galileo afterwards 

 made, on the motion of falling bodies, would have caused 

 him to reconsider his opinion that the velocity of a falling 

 body is proportional to its weight. His belief that falling 

 stars, comets, the Milky Way, winds, earthquakes, and some 

 other phenomena were dependent in some way on the ex- 

 istence of a peculiar dry vapour given off by the Earth,* had 

 little else to support it besides abstract reasoning. An 

 examination of the skeleton of a snake would have prevented 

 him from asserting that it had thirty ribs,t and, if he had 

 taken a freshwater eel, a conger, and a bass, skate, or other 

 large fish, and had laid these open to expose the anterior 

 part of the alimentary canal, he would not have stated that 

 a few fishes, like the conger and the freshwater eel, have an 

 oesophagus, but that it is small even in these,! or that the 

 oesophagus is entirely wanting in some fishes, and is but 

 short in others. § He had probably noticed that, in some 

 fishes, the oesophagus was short, and that it was often 

 difficult to determine where it ended and the stomach began, 

 but he did not carry his observations far enough. 



The mistakes made by Aristotle have been made by many 

 since his time. There were some cases, however, in which it 

 would be unreasonable to expect Aristotle to succeed in 

 arriving at the truth, even though he had made numerous 

 observations and otherwise carefully followed the rules of 

 his method. His want of success would follow naturally 

 from the want of proper instruments of observation, and an 

 inevitable inability to appreciate the very complicated nature 

 of the phenomena themselves. Consider, for instance, his 

 description, chiefly in H. A. vi. c. 3, of the phenomena of 

 incubation of a bird's egg. He evidently believed that the 

 heart was the first part to be developed. His researches on 

 the incubation of a bird's egg, however, were original, and 

 constitute one of the best proofs that he was a careful 

 observer. Another statement, probably the result of many 

 observations, may also be considered. He says that all 

 fishes which have scales are oviparous. || Comparatively 

 recent observations have shown that there are many excep- 

 tions to this, yet Aristotle can scarcely be adversely criticized 



* MefeoroZ. i. and ii. f If.^. ii. c. 12, s. 12. | H. .4. ii. c. 12, s. 3. 

 § P. A. iii. c. 14, 675a. || H. A. ii. c. 9, s. 6. 



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