Isaac Newton represented Cambridge University as a Member of Parliament in 1689 and 1690. In 1690, his health failed. This illness was probably a nervous breakdown brought on by many years of working long hours and enduring too much stress. Eventually he fully recovered. For the next few years, Newton pursued his other great love studying the Bible. The books he wrote included Chronology of Ancient Kingdoms and Observations Upon the Prophecies of Daniel.In 1696, the government appointed Newton to the post of Warden of the Mint. He supervised the replacement of Englands old and damaged coins with those which were new and more durable, and even helped break up a counterfeiting ring.
In 1701, Newton began another short term as parliamentarian. Two years later he was elected president of the Royal Society. His re election to that position every year for the rest of his life showed the high esteem in which he was held by fellow scientists. Now that he had returned to science, Newton published his earlier work on light. His book, Optiks, contained both his own findings and suggestions for further research. His country officially recognized his work in 1705 when he became the first person to receive a knighthood for scientific achievement.