John Wallis (1616–1703). Mathematics, Music Theory, and Cryptography in 17th Century Oxford Oxford University Mathematical Institute, 9 June 2016

Leaving the historical accuracy of Stebbing’s statement aside, the word ‘tetractys’— unfamiliar to us as it may be—appears to have received much attention from the ancient Pythagoreans. Functioning as a mystical symbol, it gained numerous titles, amongst which ‘the world’, ‘the heaven’, ‘necessity’, ‘Atlas’ and ‘God’. The aim of this lecture is to provide an introduction to ancient Greek ‘theory of numbers’, from the alleged investigations of the so-called Pythagoreans up to the origins of algebra in the writings of Diophantus of Alexandria.