Timaeus is one of Plato's dialogues, mostly in the form of a long monologue given by the titular character Timaeus of Locri, written c. 360 BC. The work puts forward speculation on the nature of the physical world and human beings and is followed by the dialogue Critias. Participants in the dialogue include Socrates, Timaeus, Hermocrates, and Critias. Some scholars believe that it is not the Critias of the Thirty Tyrants who is appearing in this dialogue, but his grandfather, who is also named Critias. It has been suggested that Timaeus influenced a book about Pythagoras, written by Philolaus.