The rude observations commenced by the Baby- 

 lonians were continued with gradually improving 

 instruments first by the Greeks and afterward by 

 the Arabs but the results failed to afford any insight 

 into the true relation of the earth to the heavens. 

 What was most remarkable in this failure is that, to 

 take a first step forward which would have led on to 

 success, no more was necessary than a course of abstract 

 thinking vastly easier than that required for working 

 out the problems of geometry. That space is infinite 

 is an unexpressed axiom, tacitly assumed by Euclid 

 and his successors. Combining this with the most 

 elementary consideration of the properties of the tri- 

 angle, it would be seen that a body of any given size 

 could be placed at such a distance in space as to appear 

 to us like a point. Hence a body as large as our 

 earth, which was known to be a globe from the time 

 that the ancient Phoenicians navigated the Mediter- 

 ranean, if placed in the heavens at a sufficient distance, 

 would look like a star. The obvious conclusion that 

 the stars might be bodies like our globe, shining either 

 by their own light or by that of the sun, would have 

 been a first step to the understanding of the true 

 system of the world. 



There is historic evidence that this deduction did 

 not wholly escape the Greek thinkers. It is true that 

 the critical student will assign little weight to the cur- 

 rent belief that the vague theory of Pythagoras that 

 fire was at the centre of all things implies a concep- 

 tion of the heliocentric theory of the solar system. But 

 the testimony of Archimedes, confused though it is in 

 form, leaves no serious doubt that Aristarchus of Samos 



