In the Odyssey, Odysseus sacrificed two black sheep and let the dead that he wished to speak with drink of the blood. Not until then did they recognise him. In the same way the dead girl regain some of her old self by drinking of the blood in the lekythos.
Protagoras was a pre-Socratic Greek philosopher. Very few fragments of his works have survived, but he is believed to have created a major controversy during ancient times through his statement that man is the measure of all things. An another fragment from his lost work On the Gods also suggests Protagoras was a proponent of agnosticism: "Concerning the gods, I have no means of knowing whether they exist or not or of what sort they may be, because of the obscurity of the subject, and the brevity of human life".
@Protagoras - That seems to be a great take on the gods, as far as the real world is concerned.