(alike in all their parts) are a straight line, a circle, and a cylindrical helix
1;
(11) (in the note on I. 10) on the question whether a line is made up of indivisible parts (
ἀμερῆ), as affecting the problem of bisecting a given straight line
2;
(12) (in the note on I. 35) on
topical, or
locus-theorems
3, where the illustration of the equal parallelograms described between a hyperbola and its asymptotes may also be due to Geminus
4.
Other passages which may fairly be attributed to Geminus, though his name is not mentioned, are the following:
(1) in the prologue, where there is the same allusion as in the passage (8) above to a remark of Aristotle that it is equally absurd to expect scientific proofs from a rhetorician and to accept mere plausibilities from a geometer
5;
(2) a passage in the prologue about the subject-matter, methods, and bases of geometry, the latter including axioms and postulates
6;
(3) another on the definition and nature of
elemenis7;
(4) a remark on the Stoic use of the term axiom for every simple statement (
ἀπόφανσις ἁπλῆ)
8;
(5) another discussion on theorems and problems
9 in the middle of which however there are some sentences by Proclus himself
10.
(6) another passage, in connexion with Def. 3, on lines including or not including a figure (with which cf. part of the passage (4) above)
11;
(7) a classification of different sorts of angles according as they are contained by simple or mixed lines (or curves)
12;
(8) a similar classification of figures
13, and of plane figures
14;
(9) Posidonius' definition of a
figure15;
(10) a classification of triangles into seven kinds
16;
(11) a note distinguishing lines (or curves) producible indefinitely or not so producible, whether forming a figure or not forming a figure (like the “single-turn spiral”
)
17;
(12) passages distinguishing different sorts of problems
18, different sorts of theorems
19, and two sorts of converses (complete and partial)
20;
(13) the definition of the term “porism”
as used in the title of Euclid's
Porisms, as distinct from the other meaning of “corollary”
21;
(14) a note on the Epicurean objection to I. 20 as being obvious even to an ass
22;
(15) a passage on the properties of parallels, with allusions to