those said to be “advanced”) with a modest (and frequently less than mod-

est) mathematical baggage, led me to a Draconian renewal of the themes

of reﬂection I proposed to my students, and gradually to myself as well.

**It seemed important to me to start from an intuitive baggage common to**

everyone, independent of any technical language used to express it, and

anterior to any such language– it turned out that the geometric and topo-

everyone, independent of any technical language used to express it, and

anterior to any such language

logical intuition of shapes, particularly two-dimensional shapes, formed such

a common ground.