Acoustic recognition, too, is more important and significant for art than one might at first suppose. We find even in children who repeat a simple melody indefatigably that pleasure in repetition forms a psychological basis for a physiological impulse, and in the musical pleasures of adults this feeling is much stronger.[283] The playful feature is emphasized when acoustic conditions vary, as in changed pitch or some other modification, so that overcoming difficulty enters. Potpourri and variations are instances. In Wagner’s music there is a peculiar satisfaction in the emergence of a leading motive from the overwhelming mass of tones; like a friendly island rising in the midst of surging seas. All modern music, indeed, is evolved from the intricacies and modifications of such acoustic play; to follow them and identify the unity in variety is a pleasure which grows with the hearer’s technical appreciation, until at last, in fuguelike movements, actual beauty is subordinated to the artfully ordered formal features of the composition. In poetry, playful repetition takes manifold forms,[284] such as rhyme, alliteration, and that chainlike reiteration of words referred to earlier. But still more ingenious and charming is the device of bringing the repetition so close on its own heels that the first impression still dwells in the mind when the second demands attention. Pure enjoyment of repetition as such is simplest when the same or similar forms are separated by a long interval, allowing the first impression to sink below the threshold of consciousness before its analogue appears. A passage of this kind occurs in Goethe’s poem quoted above, “O gieb vom weichen Pfuhle,” etc., and is still better illustrated by the similarity of the second and eighth verses of a triolet. Take this of Gleims: “Ein Triolet soll ich ihr singen? Ein Triolet ist viel zu klein, Ihr grosses Lob hineinzubringen. Ein Triolet soll ich ihr singen? Wie sollt ich mit der Kleinheit ringen, Es müsst’ ein grosser Hymnus sein! Ein Triolet soll ich ihr singen? Ein Triolet ist viel zu klein!”[285] It is but a step from this to the familiar and primitive refrain.[286] To serve this purpose, interjections, single sounds, words, and sentences are repeated after so long an interval that there can be no question of sensuous enjoyment; it becomes mere repetition. As the soothing satisfaction of a melody is produced by dwelling on the keynote, so with the refrain. This principle is even more strongly brought out in the turn, which is so prominent a feature in much lyric poetry, and also in the form originating in Spain and Portugal in which a single verse of a familiar stanza is made the keynote of a new poem. This is play to the producer and hearers as well. Such analogy of lyric form to musical variation as is shown in the “freien Glosse” actually deserves to be called variation itself.[287]