490 ADDITIONS. 



complacently plumes itself on its clear-sightedness in rejecting arbitrary 

 systems of others, is no less arbitrary in its own arguments, and often 

 no less fanciful in its inventions, than those whom it condemns. 



We cannot take a better representative of the Common Sense of the 

 ancient Greeks than Socrates : and we find that his Common Sense, 

 judging with such admirable sagacity and acuteness respecting moral 

 and practical matters, offered, when he applied it to physical questions, 

 examples of the unconscious assumptions and fanciful reasonings which, 

 as we have said, Common Sense on such subjects commonly involves. 



Socrates, Xenophon tells us (Memorabilia, iv. 7), recommended his 

 friends not to study astronomy, so as to pursue it into scientific details. 

 This was practical advice ; but he proceeded further to speak of the 

 palpable mistakes made by those who had carried such studies far- 

 thest. Anaxagoras, for instance, he said, held that the Sun was a 

 Fire : he did not consider that men can look at a fire, but they cannot 

 look at the Sun ; they become dark by the Sun shining upon them, 

 but not so by the fire. He did not consider that no plants can grow 

 well except they have sunshine, but if they are exposed to the fire they 

 are spoiled. Again, when he said that the Sun \vas a stone red-hot, 

 he did not consider that a stone heated by the fire is not luminous, and 

 soon cools, but the sun is always luminous and always hot. 



We may easily conceive how a disciple of Anaxagoras would reply 

 to these arguments. He would say, for example, as we should proba- 

 bly say at present, that if there were a mass of matter so large and so 

 hot as Anaxagoras supposed the Sun to be, its light might be as great 

 and its heat as permanent as the heat and light of the sun are, as yet, 

 known to be. In this case the arguments of Socrates are at any rate 

 no better than the doctrine of Anaxagoras. 



