We have two classic accounts of Proteus, which give wonderful insight into the ancient conception of divinities of the deep and their habitats: Homer (Odyssey 4. 363-570) and Vergil (Georgics 4. 386–528).
Homer relates that, on his return voyage from Troy, Menelaus, king of Sparta, was unduly detained on an island off the coast of Egypt (See M/L, Chapter 18). In his distress (for provisions were almost gone) he was anxious to know why he was prevented from returning home. As it turned out, he and his men would not be able to proceed on their way until great sacrifices had been made to the gods. Menelaus learned about this fact only after he had consulted Proteus, the old man of the sea. Proteus’ daughter Eidothea (or Eidotheia) took pity upon him and gave him directions necessary for finding out the truth. Menelaus and three of his best companions were to lie in ambush to ensnare Proteus. Here is how Menelaus tells of Eidothea’s assistance in tricking her father, the immortal and infallible old man of the sea, who can readily assume countless changes of form (Odyssey 4. 435–450):
Eidothea dived down into the vast cavern of the sea and brought out of the depths four skins of seals; all were freshly skinned, for she was planning to trick her father. After hollowing out in the sea-sand four beds for us, she sat waiting; and we came right up to her. She placed us in our beds, one after the other, throwing a sealskin over each of us. A most horrible ambush this was; for the pernicious odor of the sea-nurtured seals was dreadfully oppressive. For who would like to lie down beside a monster of the sea? But she herself helped us out and contrived a great boon: she brought ambrosia and placed it under each of our noses; its very sweet fragrance eliminated the seal smell.
All morning we waited, steadfast in spirit: the seals emerged from the sea in a swarm and then they lay down side by side to sleep on the shore of the sea. At midday the old man came forth from the deep and sought out his well-nourished seals; he went round and counted them all; in his reckoning we were the first, but he did not suspect any treachery. Thereupon he himself also lay down. And we rushed upon him with a shout and threw our arms about him; but the old man did not forget his devious arts. First off he became a thickly maned lion, and then a serpent, a leopard, and a great boar. And he became liquid water and a tree with lofty branches. But we held on to him firmly with steadfast spirits. Finally the devious Proteus grew weary and answered Menelaus’ questions about his return home.