26 THE HISTORY OF SCIENCE 



Only one indication need be given of the practical 

 results that flowed from Aristotle's scientific work. 

 In one of his writings he has stated that the sphe- 

 ricity of the earth can be observed from the fact that 

 its shadow on the moon at the time of eclipse is an 

 arc. That it is both spherical and small in comparison 

 with the heavenly bodies appears, moreover, from 

 this, that stars visible in Egypt are invisible in coun- 

 tries farther north ; while stars always above the 

 horizon in northern countries are seen to set from 

 countries to the south. Consequently the earth is not 

 only spherical but also not large ; otherwise this phe- 

 nomenon would not present itself on so limited a 

 change of position on the part of the observer. " It 

 seems, therefore, not incredible that the region about 

 the Pillars of Hercules [Gibraltar] is connected with 

 that of India, and that there is thus only one ocean." 

 It is known that this passage from The Philosopher 

 influenced Columbus in his undertaking to reach the 

 Orient by sailing west from the coast of Spain. 



We must pass over Aristotle's observation of a 

 relationship (homology) between the arms of man, 

 the forelegs of quadrupeds, the wings of birds, and 

 the pectoral fins of fishes, as well as many other 

 truths to which his genius for generalization led 

 him. 



In the field of botany Aristotle had a wide 

 knowledge of natural phenomena, and raised general 

 questions as to mode of propagation, nourishment, 

 relation of plants to animals, etc. His pupil and life- 

 long friend, and successor as leader of the Peripa- 

 tetic school of philosophy, Theophrastus, combined 

 a knowledge of mathematics, astronomy, botany, and 



