Heath's notes are extensive and excellent. In the notes to any given definition or proposition, he gives the whole range of commentary and mathematical development from ancient to modern (and not just western commentaries either). And most importantly, he gives both the Greek and the English, including the Greek of the commentators! In many ways, this is the perfect book: affordable, extensive and useful scholarly apparatus, original language alongside decent translation, readable fonts, and helpful diagrams. I need to get the other volumes. Thank goodness for Dover.