If the reader chance to know that in the great palace of Constantine the Great at Constantinople there was a building of red porphyry, which by special decree was made sacred to motherhood, and that here the princes of the blood were born, being in recognition called "porphyrogene," there will come to him the vision which Poe desired to evoke. The word will suggest the regal splendors of the Byzantine court at a time when the whole world babbled of its glories, and will give to the verse a richness of atmosphere which could hardly be produced by any piling up of specific details. The reader who is not in possession of this information can only stumble over the word as I did in my youth, with an aggrieved feeling of being shut out from the inner mysteries of the poem. I spoke of this as an extreme instance of the use of this form of literary language, because the knowledge needed to render it intelligible is more unusual and special than that generally appealed to by writers. It is one of those bold strokes which are tremendously effective when they succeed, but which are likely to fail with the ordinary reader. After historic allusion comes that to folk-lore, which used to be a good deal appealed to by imaginative writers. Some knowledge of old beliefs is often essential to the comprehension of earlier authors. Suckling, for instance, says very charmingly:-- But oh, she dances such a way! No sun upon an Easter day Is half so fine a sight! The reference, of course, is to the superstition that the sun on Easter morning danced for joy at the coming of the day when the Lord arose. To get the force of the passage, it is necessary to put one's self into the mood of those who believed this pretty legend. In the same way it is only to one who is acquainted with the myth of the lubber fiend, the spirit who did the work of the farm at night for the wage of a bowl of cream set for him beside the kitchen fire, that there is meaning in the lines in "L'Allegro:"-- Tells how the grudging goblin sweat To earn his cream-bowl duly set, When in one night, ere glimpse of morn, His shadowy flail hath thresh'd the corn That ten day-laborers could not end; And, stretch'd out all the chimney's length, Basks at the fire his hairy strength; And crop-full out of doors he flings, Ere the first cock his matin rings. There is much of this folk-lore language in Shakespeare, and in our own time Browning has perhaps more of it than any other prominent author. It may be remarked in passing, that Browning, who loved odd books and read a good many strange old works which are not within general reach, is more difficult in this matter of allusion than any other contemporary. References of this class are generally a trouble to the ordinary reader, and especially are young students likely to be unable to understand them readily.