NATURE 



499 



THURSDAY, JULY 17, 1913. 



ARISTARCHUS OF SAMOS. 

 Aristarchus of Samos : The Ancient Copernicus. 

 A History of Greek Astronomy to Aristarchus 

 together with Aristarchus's Treatise on the 

 Sizes and Distances of the Sun and Moon. A 

 New Greek Text with Translation and Notes. 

 By Sir Thomas Heath, K.C.B., F.R.S. Pp. 

 viii + 425. (Oxford: Clarendon Press, 1913.) 

 Price 18s. net. 



ARISTARCHUS, who flourished in the first 

 half of the third century B.C., is chiefly 

 known as the only philosopher or astronomer of 

 antiquity who taught that the earth moves round 

 the sun. This doctrine is, however, not men- 

 tioned in the only writing of his which has been 

 preserved, and the little we know about it is 

 derived from allusions to it made by subsequent 

 writers. All the same, his little book, "On the 

 Sizes and Distances of the Sun and Moon," is of 

 great importance, and Sir Thomas Heath's new 

 and critical edition, accompanied by a translation, 

 commentary, and notes, is therefore a most wel- 

 come addition to the literature of astronomical 

 history. 



Considering" that the idea of the earth being 

 in the centre of the universe reigned undisturbed 

 until less than four hundred years ago, it is one 

 of the most surprising facts in the history of 

 astronomy that its motion round the sun should 

 have been proposed more than 1700 years before 

 the time of Copernicus, and that it should only 

 have been accepted by one single philosopher, 

 Seleukus, as to whom it is not even certain that 

 he went the whole way and did not merely accept 

 the daily rotation of the earth. The editor of 

 this new edition of Aristarchus, therefore, thought 

 it desirable to prepare a lengthy introduction to 

 the work, giving an account of the progress of 

 astronomy in Greece from the time of Thales to 

 and including that of Aristarchus. Though this 

 is not the first time that an English writer has 

 dealt with this subject, Sir Thomas Heath has 

 done good work by preparing this introductory 

 memoir, which fills more than three hundred pages, 

 as he possesses special qualifications for writing 

 the history of Greek science, and there are 

 various controversial matters which cannot be too 

 much discussed — provided it is done by writers 

 who are as competent to do so as he is. The 

 author gives full references to the very copious 

 literature on the subject ; indeed, he even notices 

 some statements which he might well have 

 ignored, such as the comically exaggerated picture 

 NO. 2 28l. VOL. ^1" 



drawn by Gomperz, of how Demokritus seems to 

 have anticipated out of his inner consciousness 

 many modern discoveries. The passages in the 

 works of ancient writers from which our know- 

 ledge of early Greek astronomy is derived are 

 always given at full length in translation, which 

 many readers who may not have access to the 

 originals will find very convenient. 



The chapters on the pre-Socratic philosophers, 

 the Pythagoreans, Plato, Eudoxus, and Aristotle, 

 do not call for special notice. They deal very 

 fully and fairly with all the questions about which 

 a good deal of controversy raged fifty or sixty 

 years ago, but which may now be considered 

 finally settled. Nobody now believes that Plato 

 taught the daily rotation of the earth, or that he, 

 in his old age, was inclined to think that the 

 sun was at the centre of the universe. The de- 

 batable question is now, how astronomy can have 

 advanced so much during the sixty or seventy 

 years after the promulgation of the system of 

 concentric spheres of Eudoxus as to lead Aris- 

 tarchus to announce that the earth moved round 

 the sun in a year. 



The dominating figure of this period (as regards 

 the progress of astronomy) is not Aristotle, but 

 Herakleides of Pontus. Of him we know with 

 certainty that he taught the rotation of the earth 

 and the motion of Mercury and Venus round the 

 sun. But much greater honours were claimed 

 for him by Schiaparelli, who, in a memoir pub- 

 lished in 1898, tried to show that Herakleides 

 not only must have extended his theory from the 

 inferior to the superior planets, thus enunciating 

 the Tychonic system, but that he must also have 

 taken the next step in favour of the heliocentric 

 system. He should thus have anticipated Aris- 

 tarchus. The only alleged proof of this is a 

 passage in a lost book by Geminus (who lived 

 250 years after Herakleides) quoted by Simplicius. 

 That this very peculiarly worded passage is cor- 

 rupt is beyond a doubt ; Sir Thomas Heath shows 

 clearly that the name of Herakleides occurring in 

 it is a later interpolation, and he suggests that 

 Geminus may simply have been alluding to the 

 doctrine of Aristarchus. But in any case it is 

 impossible to get over the express statement of 

 Simplicius that Herakleides assumed the earth 

 to be in the middle, while Aetius (the compiler of 

 the " Placita Philosophorum ") distinctly says that 

 Herakleides let the earth move, "not progress- 

 ively, but in a turning manner." That is to say, 

 it stood still, but it rotated on its axis. 



There is therefore no reason to believe that Aris- 

 tarchus had any predecessor in developing first 

 the so-called system of movable excentrics, and 

 then, by a bold step, the heliocentric system. That 



