Part 5 revisits some earlier themes and takes some of them a bit further. Topics include: the indefinability of ‘good’; the mistake of modelling dialectic on mathematics; the relation of the form of the good to other forms; the sun-like form of the good versus the participand; the correlativity of intelligence and the good; the role of moral and intellectual education; the practicality of the rulers’ dialectic and how this makes it impossible for Socrates to produce examples; how the ‘ordinariness’ of this sort of reasoning is not at odds with Plato’s solemnity about it; how, even when writing the Republic, he could have envisaged dialectic as including investigations of a more theoretical and technical nature than those which (according to this book) characterize his ideal rulers; and, finally, the Republic’s stance of naïve realism about forms.