The Cambridge History of English and American Literature in 18 Volumes (1907–21).
Volume VIII. The Age of Dryden.
§ 4. Insufficient Understanding as to Equivalence in Feet
This instinctive carrying out, however, of the principles which have been shown in previous chapters as at work since the thirteenth century, at least, was not thoroughly understood by any poet except Shakespeare. His contemporaries and successors in lyric, with a few exceptions, though they fully comprehend line variety in length and the stanza symphony produced thereby, did not venture on any large proportion of equivalence in individual feet. And there was not any harm in this, for the construction of their stanzas, with alternation of long and short lines, was so intricate and varied that it almost produced the effect of foot-substitution. But, in blank verse, the result of insufficient understanding was more disastrous. They saw the writing everywhere on the wall, “Be bold!”: they omitted to notice the single warning, “Be not too bold!”