 We do not know when, precisely, Plato adopted this mode of thought, but it stands to reason that his contact with the Pythagorean school on his first voyage to Southern Italy and Sicily around 390 BC played a major role in this development. Mathematics as a model-science has several advantages. It deals with unchangeable entities that have unitary definitions. It also makes a plausible claim that the essence of these entities cannot be comprehended in isolation but only in a network of interconnections that have to be worked out at the same time as each particular entity is defined. For instance, to understand what it is to be a triangle, it is necessary – inter alia – to understand the nature of points, lines, planes and their interrelations. That Plato was aware of this fact is indicated by his somewhat prophetic statement in his introduction of the theory of recollection in the Meno, 81d: “As the whole of nature is akin, and the soul has learned everything, nothing prevents a man, after recalling one thing only – a process men call learning – discovering everything else for himself, if he is brave and does not tire of the search; for searching and learning, are, as a whole, recollection (anamnesis).” The somewhat mystifying claim of an ‘overall kinship’ is then illuminated in the famous ‘mathematical experiment’ (Me. 82b–85c). The slave finally manages, with some pushing and pulling by Socrates, and some illustrations drawn in the sand, to double the area of a given square. In the course of this interrogation, the disciple gradually discovers the relations between the different lines, triangles, and squares. That Plato regards these interconnections as crucial features of knowledge is confirmed later by the distinction that Socrates draws between knowledge and true belief (97b–98b). As Socrates argues, true beliefs are unreliable, because they behave like ‘the statues of Daedalus that easily run away as long as they are not tied down’. The requisite ‘tying down’ happens (98a) “by giving an account of the reason why. And that, Meno my friend, is recollection, as we previously agreed. After they are tied down, in the first place, they become knowledge, and then they remain in place.” This explanation indicates that, according to Plato, knowledge does not consist in a mental ‘gazing’ at isolated models, but rather in uncovering the invariant relations that constitute the objects in question. 