Timaeus (Greek: Timaios) is a theoretical treatise of Plato in the form of a Socratic dialogue, written circa 360 BC. The work puts forward speculation on the nature of the physical world. It is followed by the dialogue Critias. Speakers of the dialogue are Socrates, Timaeus of Locri, Hermocrates, Critias. Some scholars have argued that it is not the Critias of the Thirty Tyrants who is appearing in this dialogue, but his grandfather, who is also named Critias.