context: In the early years the College trained many Puritan ministers.[citation needed] (A 1643 publication said the school's purpose was "to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust".) It offered a classic curriculum on the English university model—​​many leaders in the colony had attended the University of Cambridge—​​but conformed Puritanism. It was never affiliated with any particular denomination, but many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.
question: What was the primary denomination affiliation of the school?