Part 4 addresses some questions arising. (1) Elsewhere (and, we assume, in the Republic) Plato recognizes a ‘good-making’ good – that without which all other goods lack value – which he identifies with wisdom. How does the ‘good-maker’ relate to the sun-like form? (2) The Republic recognizes a form of the good in which all good things participate. This entity cannot be straightforwardly identical with the sun-like form since the latter is interrogative whereas the former answers to the predicate of a true declarative sentence saying that something is good. How are these ‘two’ entities related? Discussion shows that the sun-like one is metaphysically prior to the participand. (3) What is the purpose of the rulers’ mathematical education? The Republic is explicit that it constitutes their induction into rationality. It neither says nor implies (so the present argument) that their ethical expertise will be couched in mathematical language, or that dialectic is responsible for a programme of grounding mathematics on ultimate metaphysical principles. (4) What is the role of the form of the good in the divine crafting of the cosmos? Does the interrogative interpretation apply here too? And is the sun-like form of the good actually a god itself?