232 SUCCESSORS OF THE GREAT GEOMETERS 
of Pontus] coining forward and saying that, even on the 
assumption that the earth moves in a certain way, while 
the sun is in a certain way at rest, the apparent irregularity 
with reference to the sun may he saved.’ Philological con 
siderations as well as the other notices which we possess 
about Heraclides make it practically certain that ‘ Heraclides 
of Pontus’ is an interpolation and that Geminus said ns 
simply, ‘a certain person’, without any name, though he 
doubtless meant Aristarchus of Samos. 1 
Simplicius says that Alexander quoted this extract from 
the epitome of the egyyga-Ls by Geminus. As the original 
work was apparently made the subject of an abridgement, we 
gather that it must have been of considerable scope. It is 
a question whether ègrjyrjcns means ‘commentary’ or ‘ex 
position ’ ; I am inclined to think that the latter interpretation 
is the correct one, and that Geminus reproduced Posidonius’s 
work in its entirety with elucidations and comments ; this 
seems to me to be suggested by the words added by Simplibius 
immediately after the extract ‘this is the account given by 
Geminus, or Posidonius in Geminus, of the difference between 
physics and astronomy ’, which seems to imply that Geminus 
in our passage reproduced Posidonius textually. 
‘ Introduction to the Phaenomena ’ attributed to Geminus. 
There remains the treatise, purporting to be by Geminus, 
which has come down to us under the title Teyivov elaaycoyrj 
els ra $ cuv 6 per a. 2 What, if any, is the relation of this work 
to the exposition of Posidonius’s Meteorologica or the epitome 
of it just mentioned? One view is that the original Isagoge 
of Geminus and the ègyyrjcns of Posidonius were one and the 
same work, though the Isagoge as we have it is not by 
Geminus, but by an unknown compiler. The objections to 
this are, first, that it does not contain the extract given by 
Simplicius, which would have come in usefully at the begin 
ning of an Introduction to Astronomy, nor the other extract 
given by Alexander from Geminus and relating to the rainbow 
which seems likewise to have come from the egijyrja-LS 3 ; 
1 Cf. Aristarchus of Samos, pp. 275-83. 
2 Edited by Manitius (Teubner, 1898), 
8 Alex. Aphr. on Aristotle’s Meteorologica, hi. 4, 9 (Ideler, ii, p. 128; 
p. 152. 10, Hayduck).