Summary of doctoral thesis: At the end of the Hippias Major, following a number of failed attempts to define τὸ καλόν (“the beautiful” or “the fine”), Socrates admits that, when he is left alone, he is overcome by the question, “when you are in such a condition [i.e., ignorant of Beauty] do you think it is better for you to live than to die?” (304e) This moment of despair and vulnerability is a surprising conclusion to a dialogue that is characterised by overwhelming irony and comic allusions. Socrates’ closing question suggests that Beauty is not merely an object of debate or a joking matter, rather, it is indispensable to leading a good life. I aim to understand why, without knowing what τὸ καλόν is, Socrates confidently values it, alongside the good and true, as central to a virtuous life. Despite the failure to find a suitable definition, the arguments Socrates offers reveal the structuring requirements of Socratic definition as well as some of the implicit beliefs Socrates holds about the nature, role, and experience of the beautiful. In the course of my research, I hope to show how this engagement with and consideration of the topic of beauty, if it was in fact penned by Plato, informs Plato’s middle period metaphysics of Forms, in particular the relation between the Form of the Good and the Beautiful. In addition to my primary interest in the role of beauty in facilitating a good life, I will also investigate the structure of Socratic definition, early Platonic ontology, the role of Socratic irony, the stylistic influence of comedy, the authenticity and dating of the dialogue, and the dialogue’s influence on later theories of aesthetics.