No scheme of ballad classification can be at all points complete and satisfactory. We have seen that it is impossible to classify the Scottish ballads according to authorship, since authors, known and proved, there are none. Scarce more practicable is it to arrange them in any regular order of chronology or locality; and even when we seek to group them with regard to type and subject, difficulties start up at every step. A convenient and intelligible division would seem to be one that recognised the ballads as Mythological, Romantic, or Historical, this last class including the lays of the foray and the chase, that cannot be assigned to any particular date--that cannot, indeed, be proved to have any historical basis at all--but can yet, with more or less of probability, be assigned to some historical or _quasi_-historical character. Besides these, there are groups of ballads that cannot be wholly overlooked--ballads in which, contrary to the prevailing spirit of this kind of poetry, Humour asserts itself as an essential element; ballads of the Sea; and Peasant ballads, of which, perhaps, England yields happier examples than Scotland--simple rustic ditties, hawked about in broad-sheets, and dating, many of them, no earlier than the present century, that seldom rise much above the doggerel and commonplace, and do not, as a rule, concern themselves with the high personages and high-strung passions of the ballad of Old Romance. No well-defined frontier can be laid down between the three chief departments of ballad minstrelsy. The pieces in which fairy-lore and ancient superstition have a prominent place--the ballads of Myth and Marvel--have all of them a strong romantic colouring; and the like may be said of the traditional songs of war and of raiding and hunting, as well as of those whose theme is the passion and tragedy of love. Romance, indeed, is the animating soul of the body of Scottish ballad poetry; the note that gives it unity and distinguishes it from mere versified history and folklore. There are few ballads on which some shadow out of the World Invisible is not cast; few where ill-happed love is not a master-string of the minstrel's harp; few into which there does not come strife and the flash of cold steel. Natheless, a broad division into ballads Supernatural, Romantic, and Martial has reason as well as convenience to recommend it; and in a loose and general way such an arrangement should also indicate the comparative age, not indeed of the ballad versions as we know them, but of the ideas and materials of which they are composed.