THE GOLDEN AGE OF GREECE 69 



PLATO AND THE ACADEMY. One of the greatest names in the 

 history of philosophy is that of Plato, and yet with Plato philosophy 

 enters upon a new phase in which it almost parts company with 

 science. Before Plato philosophy was almost wholly devoted 

 to inquiries or speculations touching the earth, the heavens, and 

 the universe, and hence was substantially "nature" or "natural" 

 philosophy. But with Plato and ever since his time the larger 

 part of philosophy has been devoted to observation and specu- 

 lation upon the human mind and its products, and has accordingly 

 often been called "mental" or "moral" as contrasted with "nat- 

 ural" philosophy. It is therefore Thales and Pythagoras, Democ- 

 ritus and Aristotle, rather than Plato and his disciples, who are 

 the protagonists of science as the word is used to-day. 



As a disciple of Socrates, Plato found it expedient to leave 

 Athens after the death of his master, and during the following 

 eleven years he travelled widely in the Mediterranean world, 

 doubtless familiarizing himself with the learning of Egypt and of 

 the Greek Ptolemies. After having been sold as a slave, re- 

 deemed and set free, Plato returned to his native city, and es- 

 tablished himself as a philosopher. While primarily a philosopher 

 rather than a mathematician, Plato, unlike his master Socrates, 

 who desired only enough mathematics for daily needs, rated 

 highly the importance of mathematics and rendered services of 

 the greatest value in its development. This was doubtless due in 

 part to the influence of Archytas, a friend of the Pythagoreans, with 

 whom he had associated during his prolonged exile. 



The register proceeds : "Plato . . . caused mathematics in gen- 

 eral, and geometry in particular, to make great advances, by reason 

 of his well known zeal for the study, for he filled his writings with 

 mathematical discourses, and on every occasion exhibited the 

 remarkable connection between mathematics and philosophy." 



"Let no one ignorant of geometry enter under my roof" was 

 the injunction which confronted Plato's would-be disciples. His 

 respect for mathematics finds interesting expression in the re- 

 marks he puts into the mouth of Socrates in the Dialogues, 

 and to him it is largely indebted for its place in higher education. 



