2. He may have been searching for the philosopher’s stone
During Newton’s lifetime he devoted decades to alchemy, known in his day in England as “chymistry”, much of which was illegal at the time, considered to be heretical. Alchemists sought a material known among them as the philosopher’s stone, a mythical substance believed to be capable of transmuting metals into gold and silver, and to give its possessor eternal life, as well as acting to restore youth and vitality. Alchemists referred to the search for the philosopher’s stone as the “Magnum Opus”, Latin for the Great Work. Because it was heretical and in some respects illegal, alchemists used various linguistic tricks in communicating with each other, including puns and other wordplay as well as outright code, Newton among them.
During Newton’s lifetime the distinction between science and superstition was vague, and literal interpretation of the Christian Bible was the dominant worldview. As part of his occult studies and alchemy experiments, Newton, besieged by deteriorating mental health, spent much of his time poring over the Book of Revelation in the belief that it contained clues which would lead him to the discoveries which were the goal of the Magnum Opus. He did not publish his works on alchemy during his lifetime, and though some believe that much of his work was destroyed in a fire accidentally started by his dog (the story is probably apocryphal), most of his work was published in 1936, and was later published online.