The sources of Elements

1. Euclid 354 authority · 1 neutral · 42 extended 397 citations · 1,347 passages

   book 1 133 passages anchored here · book 2 48 passages anchored here · book 3 48 passages anchored here · book 5 13 passages anchored here · book 6 132 passages anchored here · book 7 97 passages anchored here · book 8 23 passages anchored here · book 9 73 passages anchored here

   and 4 more chapters

   book 10 446 passages anchored here · book 11 149 passages anchored here · book 12 106 passages anchored here · book 13 79 passages anchored here

   Book V's general theory of proportion is invoked by proposition number far more than any other source, forming the logical backbone that licenses moves like alternation, ex aequali reasoning, and equality of ratios throughout the window.

   For since, as A is to B, so is C to D, therefore, alternately, as A is to C, so is B to D.

2. Elements Euclid 9 authority 9 citations · 53 passages

   book 4 42 passages anchored here · book 9 11 passages anchored here

   The passage continually cites earlier propositions and definitions of Euclid's own Elements (chiefly Books I and III, plus II.11 and its own Book IV definitions) in bracketed references as the authoritative basis for each proof step; it …

   and therefore its three angles EGD, GDE, DEG are equal to one another, inasmuch as, in isosceles triangles, the angles at the base are equal to one another.

3. De Communibus Notitiis adversus Stoicos Plutarch 1 neutral 1 citation

   book 12

   This specific work and passage of Plutarch is cited by name and section number as the source for the discussion of Democritus.

   Stoicos XXXIX 3) about Democritus above referred to.

Each stands at a single passage. The chapter carries the anchors.

book 12 6 sources

Commentary on Aristotle's Physics · History of Geometry · Method (Ephodos, addressed to Eratosthenes) · Metrica · On the Sphere and Cylinder · Quadrature of the Parabola

book 13 8 sources

Book XIV (supplement to the Elements) · Comparison of the dodecahedron with the icosahedron (second edition) · Comparison of the five regular solids (Comparison of the five figures) · Geschichte der Mathematik · Greek Geometry from Thales to Euclid · Suda (Suidas lexicon entry on Theaetetus) · scholium No. I to Eucl. XIII · unspecified work (p. 171)

The harvest records where a citation is made: the paragraph in the citing book, and the book that paragraph stands in. It does not record which page of this book is meant. Where the citing text names a locus, you will find it in the quotation.

1. Elements Euclid 9 authority 9 citations · 53 passages

   book 4 42 passages anchored here · book 9 11 passages anchored here

   The passage continually cites earlier propositions and definitions of Euclid's own Elements (chiefly Books I and III, plus II.11 and its own Book IV definitions) in bracketed references as the authoritative basis for each proof step; it …

   and therefore its three angles EGD, GDE, DEG are equal to one another, inasmuch as, in isosceles triangles, the angles at the base are equal to one another.