H. A. Kelly in "Divine Providence in the England of Shakespeare's Histories" (1970) examines political bias and assertions of the workings of Providence in (a) the contemporary chronicles, (b) the Tudor historians, and (c) the Elizabethan poets, notably Shakespeare in his two tetralogies, (in composition-order) "Henry VI" to "Richard III" and "Richard II" to "Henry V". According to Kelly, Shakespeare's great contribution, writing as a historiographer-dramatist, was to eliminate the supposedly objective providential judgements of his sources, and to distribute them to appropriate spokesmen in the plays, presenting them as mere opinion. Thus the sentiments of the Lancaster myth are spoken by Lancastrians, the opposing myth is voiced by Yorkists, and the Tudor myth is embodied in Henry Tudor. Shakespeare "thereby allows each play to create its own ethos and mythos and to offer its own hypotheses concerning the springs of action".