XVI 
SOME HANDBOOKS 
The description of the handbook on the elements of 
astronomy entitled the Introduction to the Phaenomena and 
attributed to Geminus might properly have been reserved 
for this chapter. It was, however, convenient to deal with 
Geminus in close connexion with Posidonius; for Geminus 
wrote an exposition of Posidonius’s Meteorologica related to the 
original work in such a way that Simplicius, in quoting a long 
passage from an epitome of this work, could attribute the 
passage to either Geminus or £ Posidonius in Geminus ’; and it 
is evident that, in other subjects too, Geminus drew from, and 
was influenced by, Posidonius. 
The small work De motu circulari corporum caelestium by 
Cleomedes {KXeopijSovs kvkXlkt] dtoopia) in two Books is the 
production of a much less competent person, but is much more 
largely based on Posidonius. This is proved by several refer 
ences to Posidonius by name, but it is specially true of the 
very long first chapter of Book II (nearly half of the Book) 
which seems for the most part to be copied bodily from 
Posidonius, in accordance with the author’s remark at the 
end of Book I that, in giving the refutation of the Epicurean 
assertion that the sun is just as large as it looks, namely one 
foot in diameter, he will give so much as suffices for such an 
introduction of the particular arguments used by ‘certain 
authors who have written whole treatises on this one topic 
(i.e. the size of the sun), among whom is Posidonius’. The 
interest of the book then lies mainly in what is quoted from 
Posidonius; its mathematical interest is almost nil. 
The date of Cleomedes is not certainly ascertained, but, as 
he mentions no author later than Posidonius, it is permissible 
to suppose, with Hultsch, that he wrote about the middle of