All rhythm therefore in our dancing, poetry, and music, comes to us from ancient times, and is of the same nature in these three arts: it is regular order in the succession of different kinds of motion. § =4.= The distinction between prose and poetry in their external aspects may be stated thus: in prose the words follow each other in an order determined entirely, or almost entirely, by the sense, while in poetry the order is largely determined by fixed and regular rhythmic schemes. Even in prose a certain influence of rhythmical order may be sometimes observable, and where this is marked we have what is called rhythmical or artistic prose. But in such prose the rhythmic order must be so loosely constructed that it does not at once obtrude itself on the ear, or recur regularly as it does in poetry. Wherever we have intelligible words following each other in groups marked by a rhythmical order which is at once recognizable as intentionally chosen with a view to symmetry, there we may be said to have poetry, at least on its formal side. Poetical rhythm may accordingly be defined as a special symmetry, easily recognizable as such, in the succession of syllables of differing phonetic quality, which convey a sense, and are so arranged as to be uttered in divisions of time which are symmetrical in their relation to one another. § =5.= At this point we have to note that there are two kinds of phonetic difference between syllables, either of which may serve as a foundation for rhythm. In the first place, syllables differ in respect of their _quantity_; they are either 'long' or 'short', according to the length of time required to pronounce them. In the second place, they differ in respect of the greater or less degree of force or stress with which they are uttered; or, as it is commonly expressed, in respect of their _accent_. All the poetic rhythms of the Indogermanic or Aryan languages are based on one or other of these phonetic qualities of syllables, one group observing mainly the quantitative, and the other the accentual principle. Sanskrit, Greek, and Roman poetry is regulated by the principle of the quantity of the syllable, while the Teutonic nations follow the principle of stress or accent.[3] With the Greeks, Romans, and Hindoos the natural quantity of the syllables is made the basis of the rhythmic measures, the rhythmical ictus being fixed without regard to the word-accent. Among the Teutonic nations, on the other hand, the rhythmical ictus coincides normally with the word-accent, and the order in which long and short syllables succeed each other is (with certain exceptions in the early stages of the language) left to be determined by the poet's sense of harmony or euphony.