  Barry Mazur published an article some year ago, where he showed, among other
things, that the result in the so-called mathematical passage of Plato s
Theatetus and Euclid s proposition X.9 in the Elements are very different,
while almost all historians and commentators have claimed the opposite. In this
lecture, we consider this question to try to understand how and why could have
happened such an error, this 'strange delusion' to quote Mazur.
