As we discussed in the section on the problem of the birth of a mathematical community in chapter 4 p. 135, the past was already an inevitable presence in the second century BC; not just for mathematics, but also for philosophy, medicine, grammar. As knowledge accumulated in the form especially of books, scrolls at first, codexes later, collected in the libraries of rich Romans or later of bishops and abbots, the presence of the past and its inevitability grew even larger. It is thus not surprising that late antiquity saw a proliferation of ‘deuteronomic’ texts, not only in mathematics but in practically any other form of knowledge in which the written medium played an important role. I will first try better to characterize how late ancient mathematicians behaved towards previous sources – this has been tackled in chapter 7, so here I will only say some more with reference to the same authors: Pappus, Proclus, Eutocius. Second, I will look at explicit statements these authors made about the past, at the histories they wrote. Third, I will address the question of why the past was used so extensively.