The opening soliloquy of Richard III has its roots in the self-declaration of Vice in medieval drama. At the same time, Richard's vivid self-awareness looks forward to the soliloquies of Shakespeare's mature plays. No single play marks a change from the traditional to the freer style. Shakespeare combined the two throughout his career, with Romeo and Juliet perhaps the best example of the mixing of the styles. By the time of Romeo and Juliet, Richard II, and A Midsummer Night's Dream in the mid-1590s, Shakespeare had begun to write a more natural poetry. He increasingly tuned his metaphors and images to the needs of the drama itself. Shakespeare's standard poetic form was blank verse, composed in iambic pentameter. In practice, this meant that his verse was usually unrhymed and consisted of ten syllables to a line, spoken with a stress on every second syllable. The blank verse of his early plays is quite different from that of his later ones. It is often beautiful, but its sentences tend to start, pause, and finish at the end of lines, with the risk of monotony. Once Shakespeare mastered traditional blank verse, he began to interrupt and vary its flow. This technique releases the new power and flexibility of the poetry in plays such as Julius Caesar and Hamlet. Shakespeare uses it, for example, to convey the turmoil in Hamlet's mind: After Hamlet, Shakespeare varied his poetic style further, particularly in the more emotional passages of the late tragedies. The literary critic A. C. Bradley described this style as "more concentrated, rapid, varied, and, in construction, less regular, not seldom twisted or elliptical". In the last phase of his career, Shakespeare adopted many techniques to achieve these effects. These included run-on lines, irregular pauses and stops, and extreme variations in sentence structure and length. In Macbeth, for example, the language darts from one unrelated metaphor or simile to another: "was the hope drunk/ Wherein you dressed yourself?" (1.7.35–38); "... pity, like a naked new-born babe/ Striding the blast, or heaven's cherubim, hors'd/ Upon the sightless couriers of the air ..." (1.7.21–25). The listener is challenged to complete the sense. The late romances, with their shifts in time and surprising turns of plot, inspired a last poetic style in which long and short sentences are set against one another, clauses are piled up, subject and object are reversed, and words are omitted, creating an