From Antiquity until recently, philosophers and mathematicians have continually discussed the concept of angle and its relation to archimedean and non-archimedean theories of measurement. For the first time, this book traces the history of these discussions in Greek and Arabic, from Euclid to Kamāl al-Dīn al-Fārisī, after whom the discussion was not resumed until Newton and Euler. The volume presents first editions of over twenty texts, either in Arabic or Greek and translated into Arabic, of the greatest mathematicians and philosophers of the time. The texts are here translated into French and supplemented with extensive commentary. The book begins with the definitions and propositions of Euclid on angles and measurement, followed by the Greek commentary tradition represented by Proclus and Simplicius (only extant in Arabic) and the writings of the Arabic mathematicians and philosophers from the 9th through 14th century, placing the fundamental contributions by Avicenna and Ibn al-Haytham into their historical context and showing how numerous successors produced new syntheses of their work.