226 EVOLUTION OF THE SCIENTIFIC INVESTIGATOR. 



some, was a powerful factor in the same direction. The result was 

 that, in keeping geometry pure from ideas wdiich did not belong to 

 it. it failed to form Avhat might otherwise have been the basis of 

 physical science. Its founders missed the discovery that methods 

 similar to those of geometric demonstration could be extended into 

 other and wider fields than that of space. Thus, not only the devel- 

 opment of applied geometry, but the reduction of other conceptions 

 to a rigorous mathematical form was indefinitely postponed. 



Astronomy is necessarily a science of observation pure and simple, 

 in Avhich experiment can have no place except as an auxiliary. The 

 vague accounts of striking celestial phenomena handed down by the 

 priests and astrologers of antiquity were followed in the time of the 

 Greeks by observations having, in form at least, a rude approach to 

 precision, though nothing like the degree of precision that the as- 

 tronomer of to-day would reach with the naked eye, aided by such 

 instrum(;nts as he could fashion from the tools at the conmiand of the 

 ancients. 



The rude observations commenced by the Babylonians Avere con- 

 tinued with gradually improAnng instruments — first by the Greeks 

 and afterwards by the Arabs — but the results failed to afford any 

 insight into the true relation of the earth to the heavens. '\A^iat 

 Avas most remarkable in this failure is that, to take a first step for- 

 ward which would have led on to success, no mor(> Avas necessary 

 than a course of abstract thinking A'astly easier than that required 

 for Avorking out the problems of geometry. That space is infinite is 

 an unexpressed axiom, tacitly assumed by Euclid and his successors. 

 Gombining this with the most elementary ccmsideration of the prop- 

 ertie.-i of the triangle, it Avould be seen that a body of any giA^en size 

 coidd l)e placed at such a distance in space as to ai)pe:n- to us like a 

 point. Hence, a body as large as our earth, Avhicli was knoAvn to be 

 a glol)e from the time that the ancient Phaniicians navigated the 

 Mediterranean, if placed in tlie heavens at a sufficient distance, 

 Avould look like a star. The obvious conclusion tiiat the stars might 

 Ih' I)()(lies like our globe, shining either by their own light or by that 

 of the sun, Avould haA^e been a first step to the understanding of the 

 ti'ue system of the Avorld. 



'J'here is historic evidence that (his deduction did not wholly es- 

 cape the (ire(4v thinkers. It is true that the critical student Avill 

 assign little Aveight to the cui-rent belief that the vague theory of 

 Pythagoras — that fire- Avas at the center of all things — implies a con- 

 ception of the heliocentric theory of the solar system. But the testi- 

 mony of Archimedes, confused though it is in form, leaA^es no serious 

 doubt that Aristarchus of Samos not only j^ropounded the A'iew^ that 

 the earth revolves both on its oa\ ii axis and around the sun, but that 

 he correctly remoA-ed the great stumbling-block in the Avay of this 



