The foundation of poetry, that is of the expression of human feelings in verse, is rhythm. According to Aristoxenus, the greatest metrical scholar of Greece, rhythm is the division of time into equally recurring shorter and longer parts; but it becomes perceptible only by being applied to certain movements performed in this time (τὸ ῥυθμιζόμενον). This object of rhythm is, of course, different in the different arts. In music, it is the notes of a melody (μέλος); in dance, the movements of hands and feet (σωματικὴ κίνησις); and in poetry, the words (λέξις). In ancient, and especially in Greek, poetry, rhythm was the first and chief principle of verse; and Greek poets observed this principle with the greatest consistency, measuring their lines exclusively according to the length or shortness of the syllables, without taking any notice of the rhetorical accent of each word, which depends, of course, greatly on its meaning. This metrical system, founded entirely on the beauty of sound, agrees perfectly with what we know of the plastic art of the Greeks, where also the graceful and harmonious form predominates over the emotional expression of the features. There is something analogous to be found in the primitive poetry of the Teutonic nations. The aim of their poets was to impress the audience by the strong and heroic sound of their verses; and in consequence the principle of their metrical system was purely rhythmical. In _Beowulf_, as well as in the _Hildebrandliet_, or the _Wessobrunner Gebet_, each line contains a certain number of long and highly-accented (_hochbetont_) syllables, which are further emphasised by alliteration. The rhetorical importance of these syllables does not in the least influence their metrical value.