EARLY KNOWLEDGEMETHOD OF RESEARCH. 13 



In PSYCHOLOGY, he laid his finger on the secret of the 

 question regarding this science as a branch of Physiology 

 just what our most advanced men of science proclaim it to 

 be. He saw the law of association of ideas : " Ideas/' says 

 he, " by having been together acquire a power of recalling 

 one another; or every partial representation awakes the 

 total representation of which it had been a part." (De 

 Animal) 



In ASTRONOMY he was so practical that he made 

 observations himself for he mentions an occultation of Mars 

 by the moon, and another of a star in Gemini by Jupiter. 

 (f From the rare occurrence of such phenomena, their observa- 

 tion shows that he paid considerable attention to the 

 planetary motions." He was the first plainly to intimate that 

 the earth is a round globe ; and he rectified and completed 

 the discoveries of Eudoxus an evidence of the importance 

 he attached to verification. 



In PHYSICS he was the expounder of ancient knowledge. 

 The ancients had undoubtedly made great advances in 

 physics, since we find they used glass globes filled with 

 water " for concentrating the rays of the sun, and thus 

 producing fire." The refraction of heat was well known to 

 them, since Aristophanes, in the Clouds, alludes to the use 

 of a glass lens for obtaining fire. (Dialogue between Strep- 

 siades and Socrates, beginning with ^ Tmpa . . and ending 

 with TTJS >?/$ SIKTJS.) Aristotle's work on Physics is probably 

 much mutilated, but it contains sound facts as it stands. 

 If he was not always accurate in his explanations, he never- 

 theless argued with wisdom on Meteorology, Mechanics, 

 Mathematics, Astronomy, Chemistry, Geology, etc., if we 

 may, for brevity, place these branches under one heading. 

 Doubtless he is often weak by the light of Galileo and Newton, 

 but the world took twenty centuries to produce these two phy- 

 sicists, and although Aristotle's Physics may be considered 

 inferior to some of his other writings, yet it is a beautiful 

 work, and one which is justly regarded as fundamental. 



He also wrote, and wrote with rare insight and force, 

 on Metaphysics, Ethics, Theology, Cosmogony, Art, Poetry, 

 and Politics. In this last branch he was not content, like 



