The elves still retain their distinction into _white_ and _black_. The white or good elves dwell in the air, dance on the grass, or sit in the leaves of trees; the black or evil elves are regarded as an underground people, who frequently inflict sickness or injury on mankind, for which there is a particular kind of doctors and doctresses in most parts of Scandinavia. The elves are believed to have their kings, and to celebrate their weddings and banquets, just the same as the dwellers above ground. There is an interesting intermediate class of them called in popular tradition hill-people (_haugafolk_), who are believed to dwell in caves and small hills. When they show themselves they have a handsome human form. The common people seem to connect with them a deep feeling of melancholy, as if bewailing a half-quenched hope of salvation. Their sweet singing may occasionally be heard on summer nights out of their hills, when one stands still and listens, or, as it is expressed in the ballads, lays his ear to the elf-hill; but no one must be so cruel as by the slightest word to destroy their hopes of salvation, for then the spritely music will be turned into weeping and lamentation. The Norsemen usually call the elves _hulder_ or _huldrefolk_, and their music _huldreslaat_. It is in the minor key, and of a dull and mournful sound. Norse fiddlers sometimes play it, being thought to have learned it by listening to the underground people among the hills and rocks. There is also a tune called the elfkings’ tune, which several of the good fiddlers know right well, but never venture to play, for as soon as it begins both old and young, and even inanimate objects, are compelled to dance, and the player cannot stop unless he can play the air backwards, or that some one comes behind him and cuts the strings of his fiddle. Ole Bull and Thorgeir Andunson, the people think, learned to play the fiddle from the hill-people. The little underground elves, who are thought to dwell under the houses of mankind, are described as sportive and mischievous, and as imitating all the actions of men. They are said to love cleanliness about the house and place, and to reward such servants as are neat and cleanly.