Max Weber argued in The Protestant Ethic and the Spirit of Capitalism that Calvinist self-denial resulted in a Protestant work ethic that led to the development of capitalism. Puritan authors such as John Milton, John Bunyan, Anne Bradstreet and Edward Taylor continue to be read and studied as important figures within English and American literature. A debate continues on the definition of "Puritanism". English historian Patrick Collinson argues that "There is little point in constructing elaborate statements defining what, in ontological terms, puritanism was and what it was not, when it was not a thing definable in itself but only one half of a stressful relationship." Puritanism "was only the mirror image of anti-puritanism and to a considerable extent its invention: a stigma, with great power to distract and distort historical memory." Historian John Spurr writes that Puritans were defined by their relationships with their surroundings, especially with the Church of England. Whenever the Church of England changed, Spurr argues, the definition of a Puritan also changed. The analysis of "mainstream Puritanism" in terms of the evolution from it of Separatist and antinomian groups that did not flourish, and others that continue to this day, such as Baptists and Quakers, can suffer in this way. The national context (England and Wales, as well as the kingdoms of Scotland and Ireland) frames the definition of Puritans, but was not a self-identification for those Protestants who saw the progress of the Thirty Years' War from 1620 as directly bearing on their denomination, and as a continuation of the religious wars of the previous century, carried on by the English Civil Wars. English historian Christopher Hill, who has contributed to analyses of Puritan concerns that are more respected than accepted, writes of the 1630s, old church lands, and the accusations that William Laud was a crypto-Catholic: Notable Puritans Peter Bulkley was an influential Puritan minister and founder of Concord. John Bunyan was famous for The Pilgrim's Progress. William Bradford was Plymouth Colony's Governor. Anne Bradstreet was the first female to have her works published in the British North American colonies. Oliver Cromwell was an English military and political leader and eventually became Lord Protector of the Commonwealth of England, Scotland and Ireland. He was a very religious man and was considered an independent Puritan. John Endecott was the first governor of the Massachusetts Bay Colony and an important military leader. Jonathan Edwards, evangelical