The preceding discussion of Marlowe and his contemporaries must have made it apparent that Shakespeare cannot be treated as outside of the circle, although his plays have for convenience been reserved until now. The young actor and poet learned to meet successfully the demands of the stage through an apprenticeship of hack-work, collaboration, and revision, and progressed in his art by means of adaptation and imitation. He wrote in association and rivalry with his fellow playwrights, responding like them to theatrical fashions, and feeling like them the spur of current artistic impulses. The dramatic activity that we have been discussing bears at every point upon his early work. He shared both the limitations and the incentives, bowed to the commanding influences, and rose to the opportunities for initiative which characterize this period. His dramatic career probably began two or three years later than Marlowe's, and of the plays now to be considered several were probably not written until the years following Marlowe's death. "Titus Andronicus" and the three parts of "Henry VI" belong to the early nineties and should be classed with the tragedies of blood and the chronicle histories of those years. "King John," "Richard III," and "Richard II" came somewhat later and form a part of the more advanced development of chronicle history variously represented by "Edward III," "Woodstock," and Marlowe's "Edward II." "Romeo and Juliet," in its final form perhaps still later, is a great and original masterpiece, but one still very characteristic of the dramatic period of which it is the crown and flower. How much of "Titus Andronicus" is to be regarded as Shakespeare's remains a debated question, a recent and plausible theory being that it was his revision and combination of two old plays.[14] The play, which was coupled by Jonson with "The Spanish Tragedy" as popular twenty years after its first appearance, is mainly an imitation of Kyd, though the phrasing and rhythm frequently show an advance over that author's work. In situations and various specific passages the imitation is pronounced and the motives of the Kydian type are in the main repeated. The revenge of a father for his son is opposed by villanous intrigue, involves a play within the play, and leads the hero into madness. Kyd's finer conception of a tragic hero hesitating in the face of fearful responsibility is, however, lacking; the combination of the two revenge stories--Tamora for her child murdered by Titus, and Titus in return for the murder of his children--resembles "Locrine"; and the black Aaron is, like the negro-Moor in "Alcazar," one of the many Marlowesque villains. The play surpasses current revenge plays chiefly in its unapproached orgy of mutilation, murder, and horror.