Leibniz' texts on parallel lines

pp. 124-179

in: Vincenzo Risi, Vincenzo De Risi, Leibniz on the parallel postulate and the foundations of geometry, Basel, Birkhäuser, 2016

Abstract

If, from three points on the same straight line, of which the extremes stand apart from the middle equally, three parallels meet another straight line, the sum of the extreme lines will be equal to twice the middle line.