In the Meno, Plato established the fundamental epistemological distinction between knowledge and opinion. The geometry lesson showed that the process of learning starts from opinion and proceeds towards knowledge, by a gradual understanding of the logos. This is what the boy does – he discovers why. And it is in this realization of the why (dia ti) that learning lies. In the Meno, the difference between opinion and knowledge was explained solely in terms of their respective intrinsic characteristics: opinion is unexplained, unanalysed, out of context; knowledge, on the contrary, implies a context of reasons and its object can be explained and analysed.1 In the Meno, no explicit ontology was involved. In effect, the road to Larissa was used as an example of both the object of knowledge and the object of opinion.2 Whether at the time of writing the Meno Plato did not yet have an ontology to go with his epistemological distinction, or had it already but chose not to let it transpire, as it was not strictly called for by the needs of that dialogue – this is a matter on which it is futile to speculate.