The scene seems at first an exception to the early conventional rule, which forbade the introduction of a third actor on the Greek stage. But it has been noticed that (1) Force does not speak, and (2) Prometheus does not speak till Strength and Force have retired, and that it is therefore probable that the whole work of nailing is done on a lay figure or effigy of some kind, and that one of the two who had before taken part in the dialogue then speaks behind it in the character of Prometheus. So the same actor must have appeared in succession as Okeanos, Io, and Hermes. Footnote 137: Prometheus (_Forethought_) is the son of Themis (_Right_) the second occupant of the Pythian Oracle (_Eumen_. v. 2). His sympathy with man leads him to impart the gift which raised them out of savage animal life, and for this Zeus, who appears throughout the play as a hard taskmaster, sentences him to fetters. Hephæstos, from whom this fire had been stolen, has a touch of pity for him. Strength, who comes as the servant, not of Hephæstos, but of Zeus himself, acts, as such, with merciless cruelty. Footnote 138: The generalised statement refers to Zeus, as having but recently expelled Cronos from his throne in Heaven. Footnote 139: Hephæstos, as the great fire-worker, had taught Prometheus to use the fire which he afterwards bestowed on men. Footnote 140: Perhaps, “All might is ours except o'er Gods to rule.” Footnote 141: The words indicate that the effigy of Prometheus, now nailed to the rock, was, as being that of a Titan, of colossal size. Footnote 142: The touch is characteristic as showing that here, as in the _Eumenides_, Æschylos relied on the horribleness of the masks, as part of the machinery of his plays. Footnote 143: The silence of Prometheus up to this point was partly, as has been said, consequent on the conventional laws of the Greek drama, but it is also a touch of supreme insight into the heroic temper. In the presence of his torturers, the Titan will not utter even a groan. When they are gone, he appeals to the sympathy of Nature. Footnote 144: The legend is from Hesiod (_Theogon._, v. 567). The fennel, or _narthex_, seems to have been a large umbelliferous plant, with a large stem filled with a sort of pith, which was used when dry as tinder. Stalks were carried as wands (the _thyrsi_) by the men and women who joined in Bacchanalian processions. In modern botany, the name is given to the plant which produces Asafœtida, and the stem of which, from its resinous character, would burn freely, and so connect itself with the Promethean myth. On the other hand, the Narthex Asafœtida is found at present only in Persia, Afghanistan, and the Punjaub. Footnote 145: