Isaac Newton (1642–1727) believed that important truths about religion had been lost as well as discovered. While developing his account of nature, he investigated the worship of the earliest peoples, the chronology of ancient kingdoms, and the history of Christian doctrine. These interests filled manuscripts he largely kept out of print. The Newton available to his public was only part of the scholar at work among his books.
He read the comparative learning of his predecessors closely enough to leave identifiable debts. In his notes, Noah could appear behind the pagan name Saturn, supported by a citation to sacred geography. Accounts of temples, astronomy, and the movement of peoples supplied material for a history of knowledge shared and then corrupted. Those readings gave the supposed recovery of early religion a basis in the books on his own shelves.
His notes headed “Out of Cudworth” show how actively he worked with this inheritance. Ralph Cudworth (1617–1688) had treated ancient accounts of spiritual powers as part of a defence of belief in God. Newton drew on the collection while regarding practices of this kind as departures from an earlier and purer worship. He accepted useful testimony without accepting the purpose for which it had been assembled.
His inquiry into Christianity made that independence dangerous. He concluded that the Trinity had become established through a departure from the earliest faith, and his work on biblical texts examined passages used to support it. Restoration therefore required historical discrimination within Christianity as well as comparison with pagan religion. What later churches treated as essential might, in his judgment, be an addition that had displaced the original teaching.
Publishing such conclusions could have threatened his Cambridge position. Keeping them private protected him but also limited the part they played in the religious controversies of his lifetime. Their survival lets us see how deeply the search for original truth entered the work of a figure usually remembered for discovery in mathematics and physics. The consequences of making a similar religious argument public would become visible in the career of his successor at Cambridge.