  Shortly after returning to London, Berkeley composed the Theory of Vision, Vindicated and Explained, a defense of his earlier work on vision, and the Analyst, an acute and influential critique of the foundations of Newton’s calculus. In 1734 he was made Bishop of Cloyne, and thus he returned to Ireland. It was here that Berkeley wrote his last, strangest, and best-selling (in his own lifetime) philosophical work. Siris (1744) has a three-fold aim:  to establish the virtues of tar-water (a liquid prepared by letting pine tar stand in water) as a medical panacea, to provide scientific background supporting the efficacy of tar-water, and to lead the mind of the reader, via gradual steps, toward contemplation of God. Berkeley died in 1753, shortly after moving to Oxford to supervise the education of his son George, one of the three out of seven of his children to survive childhood.