CONTEMPLATION OF THE UNIVERSE. 105 



mena. The natural philosophy of the Ionic physiologists 

 was directed to the primary principle of origin or production, 

 or to the changes of form, of a single elementary substance. 

 In the mathematical symbolism of the Pythagoreans, in their 

 considerations on number and form, there is disclosed, on 

 the other hand, a philosophy of measure and of harmony. 

 This Doric Italic school, in seeking every where for numeri- 

 cal elements, from a certain predilection for the relations of 

 number which it recognized in space and in time, may be 

 said to have laid the foundation, in this direction, of the 

 future progress of our modern experimental sciences. The 

 history of the contemplation of the universe, in my view, 

 records not so much the often recurring fluctuations between 

 truth and error, as the principal epochs of the gradual ap- 

 proximation towards a just view of terrestrial forces and 

 of the planetary system. It shews that thfc Pythagoreans, 

 according to the report of Philolaus of Croton, taught the 

 progressive movement of the non-rotating earth, or its 

 revolution around the hearth or focus of the universe (the 

 central fire, Hestia) ; whereas Plato and Aristotle imagined 

 the earth to have neither a rotatory nor a progressive move- 

 ment, but to rest immoveably in the center. Hicetas of 

 Syracuse (who is at least more ancient than Theophrastus), 

 Heraclides Ponticus, and Ecphantus, were acquainted with 

 the rotation of the earth around its axis ; but Aristarchus of 

 Samos, and especially Seleucus the Babylonian who lived a 

 century and a half after Alexander, were the first who knew 

 that the earth not only rotates, but also at the same time re- 

 volves around the sun as the center of the whole planetary sys- 

 tem. And if, in the middle ages, fanaticism, and the still pre- 

 vailing influence of the Ptolemaic system, combined to bring 



