The expressiveness of rhythm is like that of music, vague and objectless, for which reason rhythm is properly called the music of verse. Almost everything in a general way which we have said about the expressiveness of music applies to poetic rhythm. This expressiveness cannot be translated into words with any exactness; the most that can be done is to find a set of words into which it will roughly fit, leaving much vacant space of meaning. That the emotional values of rhythms have character is, however, proved by the fact that some rhythms are better vehicles for certain kinds of thought than others are. Yet it often happens that, just as, in song or opera, the same melody is used to express joy or grief, love or religious emotion, so approximately the same rhythmic form is employed in the expression of apparently antagonistic emotions. Nevertheless, this fact is not fatal to expression; for, in the first place, there is much variety of rhythm within a given metrical form, so that what superficially may seem to be the same rhythm is really a different one; and, in the second place, as we have already observed in the case of music, there is much--in form and energy of movement--which contrasting emotions have in common, and this may be expressed in the rhythmic type. Think of the wide sweep of emotions which have been expressed in the sonnet form! Yet consider what varieties of rhythm and speech melodies are possible within this form, and how, nevertheless, there is an identity of character in all sonnets--how they are all thoughtful, all restrained, yet unfaltering in their movement! Without going into details, which would lie beyond the scope of general sthetics, it is possible to state the following broad facts (compare the similar facts relating to melody) with reference to poetic rhythms: a rising rhythm expresses striving or restlessness; a falling rhythm, quiet, steadfastness. There is, however, no absolute contrast between the two kinds, because a falling rhythm is still a rhythm, and that means a movement which necessarily contains something of instability and unrest. The contrast is sharpest in the anapestic and dactylic, less sharp in the trochaic and iambic. Many a trochaic rhythm becomes in effect iambic when the division of the thought moments and the distribution of the pauses make the rhythm rise after the first few words; and conversely, many an iambic rhythm becomes trochaic through a similar shift in the attention. Within a single line, therefore, there may be both rising and falling pulsations. Much of the rare beauty of poetry comes from such subtle combinations of rhythmic qualities.