Leon (Greek: Λέων) was an Ancient Greek mathematician and pupil of Neocleides,[1] who was active from around 370 to 340 BCE.[2] His book Elements was overshadowed by Euclid's work of the same name.

Proclus states the following[3] in his Commentary on the First Book of Euclid's Elements:

But Neoclides was junior to Leodamas, and his disciple was Leon; who added many things to those thought of by former geometricians. So that Leon also constructed elements more accurate, both on account of their multitude, and on account of the use which they exhibit: and besides this, he discovered a method of determining when a problem, whose investigation is sought for, is possible, and when it is impossible.


  1. ^ Gow, James (1884), A Short History of Greek Mathematics, University Press, p. 183, Of Neocleides and his pupil Leon also, we know no more than the Eudemian summary tells us, in which the only important fact is that Leon wrote an improved 'Elements' and treated particularly of diorismus.
  2. ^ A New History of Greek Mathematics, Cambridge: Cambridge University Press, 2022, ISBN 978-1-108-83384-4.
  3. ^ Thomas Taylor, The Philosophical and Mathematical Commentaries of Proclus on the First Book of Euclid's Elements Vol. 1 (1788)