The thesis argues that a basic ontology of dóxa and appearances (and more in general mental episodes) can be gleaned from a careful analysis of Plato's early dialogues. To this aim, the first part (chapter 1) discusses the main issues concerning Plato's language of dóxa and appearances, both from the linguistic and from the philosophical point of view, and argues that dóxa is best understood as judgement. The second part develops a three-stage argument: chapter 2 argues that dóxa and appearances are for Plato affections (páthe); chapter 3 that affections are for Plato fundamentally relational events; chapter 4 that, therefore, appearances are for Plato fundamentally relational events. The third and last part (chapter 5) investigates Plato's ontology of evaluative appearances (and desire) by focussing on the interplay between the ontology of appearances and the ontology of values (“goods and evils”) as one can extract it from the dialogue Gorgias. The three parts are secluded within a general introduction and conclusions. Four appendices complement the thesis with: a philosophical glossary of mental events; a table of frequencies of terms for mental episodes in the Platonic corpus; a list of all the occurrences of 'phaínomai' and 'dokéo' in the early dialogues; and a semi-formal appendix discussing the logical form of Plato's statements about metaphysical explanations.