310 SCIENCE PROGRESS 



does not constitute science. You want the connecting-links and generalisations 

 which were supplied by the old philosophers, who discussed the elemental notions 

 which brought the facts into relationship with each other. 



The desire to understand nature is as old as the wish to turn its manifestations 

 to practical use. Pure Science and Applied Science have grown up separately, 

 if not independently, and occasionally they came into conflict on account of the 

 fundamental difference of their outlook. We must agree with Plato that it was 

 not the men who observed the rising and setting of the stars who should be classed 

 as astronomers, but those who investigated the spheres of the heavens and the 

 great harmony of the universe. This, according to him, is the only matter 

 worthy of a humanity imbued with the spirit of the gods. The Greek philosophers 

 observed nature, though, unfortunately, they confined themselves to those facts 

 which came under their daily notice. They observed, but did not attempt to 

 experiment ; not, at any rate, in a systematic manner. The sense of harmony 

 was for ever so strongly present in their minds that they were led astray by the 

 untrained instinct of their inner consciousness. Nevertheless, if pure science be 

 defined by its guiding motive, its founders were the Greek philosophers, and not 

 the nomad tribes who used the polar star to show them the way at night. The 

 period of Greek science includes the teaching of Thales, Pythagoras, and Anax- 

 agoras, the originator of the atomic theory. Democritus (460-370 B.C.) was the 

 first to teach the corpuscular theory of light ; but the preponderating influence of 

 Greek philosophy on the science of the Middle Ages centres in the teaching 

 of Aristotle, who more than anyone else took a comprehensive view of the whole 

 range of human thought. 



Science, according to Huxley, is organised common sense ; it would be more 

 correct to say that science is the organiser of common sense. To Aristotle it 

 seemed common sense that a body unacted on by a force must be at rest. 

 If it be set in motion and continue to move, he found himself called upon 

 to explain the continuance of its motion as well as its initiation. Our better- 

 trained minds distinguish between a motion in a straight line with unchanging 

 velocity, and one in which either the direction or the velocity alters. The former 

 is identical with the state of rest, which can only be relative to other bodies. The 

 interval of nineteen hundred years between Aristotle and Galileo marks the 

 progress in the common-sense view of what is implied by absence of force. Never- 

 theless, the guiding motive of Pure Science was always the same. Much has been 

 written about the evil influence which the later followers of Aristotle had on the 

 progress of science ; but we must not blame the master because during a particu- 

 larly barren period the pupils stuck to his errors and disregarded the spirit that 

 pervaded his teaching. His position in the history of science rests on the clear 

 view he had of the problems that had to be solved. What he cared for was Pure 

 Science as he understood it, and as we ought to understand it. If anyone doubt 

 that he had an influence on the life of the nation, let him be referred to the testi- 

 mony of Alexander the Great. " I honour Aristotle," he said, " as I honour my 

 father, because while one has given me life, the other has made it worth living." 



Aristotle was followed by Euclid (330-275 B.C.), Archimedes (287-212 B.C.), and 

 after a considerable interval Ptolemajus (A.D. 70-147). While Rome was busy 

 enforcing its will on the world by military conquests, the centre of culture shifted 

 to Alexandria. But for a time it still remained Greek culture. By the murder of 

 Hypatia in the year 414 the Greek period finally closed, and for a thousand years 

 science had to take refuge under the protection of the Arabs. The search for 

 truth can only flourish in an atmosphere which tolerates differences of opinion ; 



