----------------+

The last step of the complication, which can only be indicated here, and
will be developed in a later chapter, comes with the mutual adjustment
of the natural prose rhythm and the metrical pattern of the verse. Such
a sentence as the following has its own peculiar rhythms: "And, as
imagination bodies forth the forms of things unknown, the poet's pen
turns them to shapes, and gives to airy nothing a local habitation and a
name." Now read it as verse, and the rhythms are different; both the
meaning and the music are enhanced.

And as imagination bodies forth
The forms of things unknown, the poet's pen
Turns them to shapes, and gives to airy nothing
A local habitation and a name.
SHAKESPEARE, Midsummer Night's Dream, V, i.

These then are the problems and the difficulties. The solutions can be
only partial and tentative, but they are the best we are able to obtain
with our present knowledge and our present capabilities of analysis. As
science today has advanced in accuracy of knowledge and understanding of
the facts of nature far beyond the powers of our ancestors to imagine,
so in the future psychologists may, and let us hope will, enable us to
comprehend the subtleties of metrical rhythm beyond our present power.
Yet there will always remain, since the ever-inexplicable element of
genius is a necessary part of all art, a portion which no science can
describe or analyze.

* * * * *

_The Psychology of Rhythm._ That nearly all persons have a definite
sense of rhythm, though sometimes latent because of defective education,
is a familiar fact. The origin and source of this sense is a matter of
uncertainty and dispute. The regular beating of the heart, the regular
alternation of inhaling and exhaling, the regular motions of walking,
all these unconscious or semi-conscious activities of the body have been
suggested; and they doubtless have a concomitant if not a direct
influence on the rhythmic sense. Certainly there is an intimate relation
between the heart action and breath rate and the external stimulus of
certain rhythmic forces, as is shown by the tendency of the pulse and
breath to adapt their _tempo_ to the beat of fast or slow music. But
this can hardly be the whole explanation. More important, from the
psychological point of view, is doubtless the alternation of effort and
fatigue which characterizes our mental as well as physical actions.