Acknowledgments
This paper is based on an invited lecture at the conference ‘Mathematical Biography: A MacTutor Celebration’, St Andrews University, September 2016. The author is grateful for the discussions at this meeting and at invited presentations in the ‘Seminar SAW: Mathematical Sciences in the Ancient World’, Paris, May 2016 and the ‘27th Novembertagung: History and Philosophy of Mathematical Practice’, Sandbjerg, November 2016.
Disclosure statement
No potential conflict of interest was reported by the author.