8 THE OCEAN. [Book I. 



sion of effects resulting from the earth's motion, to 

 commence by recalling to mind what om:* knowledge 

 of that motion is. 



It is only recently in the historical period that 

 the fact of the earth being in motion at all has been 

 clearly realised. Scarcely more than three hundred 

 years ago its immobility was regarded as an obvious 

 fact. That the position of the earth was fixed and 

 unchanging was supposed to be demonstrated by the 

 clear and simple evidence of the senses, and the idea 

 of its being in motion was regarded as an offspring 

 of intellectual aberration. 



It is true that nearly two thousand years before 

 the period just mentioned some keen observers of 

 natural phenomena perceived that the earth was 

 actually in motion ; ^ but, though this truth was so 



between the equator and the poles amounting to about thirteen 

 miles ; thus giving what may practically be regarded as an d, priori 

 demonstration of its paramount influence. 



^ ' It was the ancient opinion of not a few, in the eai'liest ages 

 of philosophy, that the fixed stars stood immovable in the highest 

 parts of the world ; that under the fixed stars the planets were 

 carried about the sun ; that the earth, as one of the planets, de- 

 scribed an annual course about the sun, while, by a diurnal motion, 

 it was in the meantime revolved about its own axis ; and that the 

 sun, as the common fire which served to warm the whole, was 

 fixed in the centre of the universe. 



* This was the philosophy taught of old by Philolaus, Aris- 

 tarchus of Samos, Plato in his riper years, and the whole sect of 

 the Pythagoreans; and this was the judgment of Anaximander, 

 more ancient than any of them; and of that wise king of the 

 Romans, Numa Pompilins, who, as a symbol of the figure of the 

 world, with the sun in the centre, erected a temple in honour of 



