Another class of allusions frequent in literature is the mythological. Here also we find phrases which have passed so completely into every-day currency that we hear and use them almost without reflecting upon their origin. "Scylla and Charybdis," "dark as Erebus," "hydra-headed," and "Pandora's box," are familiar examples. We speak of "a herculean task" without in the least calling to mind the labors of Hercules, and employ the phrase "the thread of life" without seeming to see the three grisly Fates, spinning in the chill gray dusk of their cave. We have gone so far as to condense a whole legend into a single word, and then to ignore the story. We say "lethean," "mercurial," "aurora," and "bacchanalian," without recalling their real significance. It is obvious how a perception of the original meaning of these terms must impart vividness to their use or to their understanding. There are innumerable instances, more particular, in which it is essential to know the force of a reference to old myths, lest the finer meaning of the author be altogether missed. In "The Wind-Harp" Lowell wrote:-- I treasure in secret some long, fine hair Of tenderest brown.... I twisted this magic in gossamer strings Over a wind-harp's Delphian hollow. In the phrase "a wind-harp's Delphian hollow" the poet has suggested all the mysterious and fateful utterances of the abyss from which the Delphic priestess sucked up prophecies, and he has prepared the comprehending reader for the oracular murmur which swells from the instrument upon which have been stretched chords twisted from the hair of the dead loved one. To miss this suggestion is to lose a vital part of the poem. When Keats writes of "valley-lilies whiter still than Leda's love," unless there come instantly to the mind the image of the snowy swan whose form Jove took to win Leda, the phrase means nothing. The woeful cry in "Antony and Cleopatra," The shirt of Nessus is upon me; teach me, Alcides, thou mine ancestor, thy rage, is full of keen-edged horror when one recalls the garment poisoned with his own blood by which the centaur avenged himself on Hercules. In a flash it brings up the picture of the demigod tearing his flesh in more than mortal agony, and calling to Philoctetes to light the funeral pyre that he might be consumed alive. It is not needful to multiply examples since they so frequently present themselves to the reader. The only point to be made is that here we have another well defined division of literary language.