John Marshall has argued that a number of passages in the "Letter" demonstrate that Locke believed that Catholics "in their terms of worship and religious speculative beliefs...deserved their worship to be free". Marshall also notes that "The combination of Locke’s comments in the Letter suggest that during composition ... Locke was once again struggling over how to discriminate between the series of associated political principles which for him made Catholics intolerable, and the religious worship and other religious beliefs of Catholics which deserved toleration." A confirmation of these positions seems to come from a 2019 discovery of a previously unknown manuscript, dated to 1667-8, titled "", in which Locke makes his earliest arguments for religious toleration.