The divine Pythagoras chose not to leave us anything of his own, but if we may judge by Ocellus the Leucanian and Archytas and his other disciples, he did not prefix “Joy to you” or “Do well,” but told them to begin with “Health to you.” At any rate all his school in serious letters to each other began straightway with “Health to you,” as a greeting most suitable for both body and soul, encompassing all human goods. Indeed the Pentagram, the triple intersecting triangle which they used as a symbol of their sect, they called “Health.” In short they thought that health included doing well and joy, but that the converse did not altogether hold. Some of them called the Quaternion, The sum of the first four integers, i.e. 1 + 2 + 3 + 4 = 10. their most solemn oath, which made for them the perfect number, the Beginning of Health. Philolaus, for example.