  Both lectures focus on the first part of the so-called 'mathematical part' of
Plato's Theaetetus. In this passage, the young Theaetetus briefly recounts the
mathematical lesson given by the geometer Theodorus. The first lecture delves
into the figures drawn by Theodorus, while the second explores his methods of
proof. Here, we present a new translation and a new interpretation of this
passage. Both lectures are based on a collaborative work in progress with Luc
Brisson.
