“Let no one ignorant of geometry enter here,” was written over the entrance to Plato’s Academy, reflecting the philosopher’s belief that geometry was essential to understand his doctrine of ideas. For Plato, in fact, any empirical element, accessible to the senses, is produced from its universal abstract prototype, the “idea,” a sort of mold that shapes all the material occurrences of a given thing. In this sense, geometric knowledge represented “knowledge that exists eternally, not something that comes into being at some moment and then ceases to exist.”