Here the rhythm is systematized according to regular laws, and so becomes metrical. The effect upon the ear in prose is largely due to rhythm, but metrical effects are entirely within the province of poetry.
This difference between rhythmical and metrical language would seem to be sufficiently obvious, but the difficulty which many students have in appreciating it may make it worth while to give another illustration. The following passage from Edmund Burke, that great master of sonorous English, is strongly and finely rhythmical:—
Because we are so made as to be affected at such spectacles with melancholy sentiments upon the unstable condition of mortal prosperity, and the tremendous uncertainty of human greatness; because in those natural feelings we learn great lessons; because in events like these our passions instruct our reason; because when kings are hurled from their thrones by the Supreme Director of this great drama, and become objects of insult to the base, and of pity to the good, we behold such disasters in the moral, as we should behold a miracle in the physical order of things.—Reflections on the Revolution in France.
So markedly rhythmical is this, indeed, that it would take but little to change it into metre:—
Because we are so made as to be moved by spectacles like these with melancholy sentiments of the unstable case of mortal things, and the uncertainty of human greatness here; because in those our natural feelings we may learn great lessons too; because in such events our passions teach our reason well; because when kings are hurled down from their thrones, etc.
There is no longer any dignity in this. It has become a sort of sing-song, neither prose nor yet poetry. The sentiments are not unlike those of a familiar passage in Shakespeare:—
This is the state of man; to-day he puts forth
The tender leaves of hopes; to-morrow blossoms,
And bears his blushing honors thick upon him:
The third day comes a frost, a killing frost;
And,—when he thinks, good easy man, full surely
His greatness is a ripening,—nips his root,
And then he falls, as I do.
Henry VIII., iii. 2.
In the extract from Burke a sense of weakness and even of flatness is produced by the rearrangement of the accents so that they are made regular; while in the verse of Shakespeare the sensitive ear is very likely troubled by the single misplaced accent in the first line. In any mood save the poetic metre seems an artificiality and an affectation, but in that mood it is as natural and as necessary as air to the lungs.
Besides being metrical the language of poetry must be imaginative. By imaginative language is meant that which not only conveys imaginative conceptions, but which is itself full of force and suggestion; language which not only expresses ideas and emotions, but which by its own power evokes them. Imaginative language is marked by the most vivid perception on the part of the writer of the connotive effect of words; it conveys even more by implication than by direct denotation. It may of course be used in poetry or prose. In the passage from Job just quoted, the use of such phrases as "empty place," "hangeth the earth upon nothing," convey more by what they suggest to the mind than by their literal assertion. The writer has evidently used them with a vital and vivid understanding of their suggestiveness. He realizes to the full their office to convey impressions so subtle that they cannot be given by direct and literal diction.
Poetry is made up of words and phrases which glow with this richness of intention. When Shakespeare speaks of skin "smooth as monumental alabaster," how much is added to the idea by the epithet "monumental," the suggestion of the polished and protected stone, enshrined on a tomb; how much is due to association and implication in such phrases as the "reverberate hills," "parting is such sweet sorrow," "the white wonder of dear Juliet's hand," "and sleep in dull, cold marble,"—phrases all of which have a literal significance plain enough, yet of which this literal meaning is of small account beside that which they evoke. Poetic diction naturally and inevitably melts into figures, as when we read of "the shade of melancholy boughs," "the spendthrift sun," "the bubble reputation," "the inaudible and noiseless foot of time;" but the point here is that even in its literal words there is constantly the sense and the employment of implied meanings. It is by no means necessarily figures to which language owes the quality of being imaginative. Broadly speaking, a style may be said to be imaginative in proportion as the writer has realized and intended its suggestions.