evidence: There is another feature of Plato's writings that makes him distinctive among the great philosophers and colors our experience of him as an author. Nearly everything he wrote takes the form of a dialogue. (There is one striking exception: his Apology, which purports to be the speech that Socrates gave in his defense — the Greek word apologia means "defense" — when, in 399, he was legally charged and convicted of the crime of impiety. However, even there, Socrates is presented at one point addressing questions of a philosophical character to his accuser, Meletus, and responding to them. In addition, since antiquity, a collection of 13 letters has been included among his collected works, but their authenticity as compositions of Plato is not universally accepted among scholars, and many or most of them are almost certainly not his. Most of them purport to be the outcome of his involvement in the politics of Syracuse, a heavily populated Greek city located in Sicily and ruled by tyrants.)