James Ussher was one of the most influential theologians of the early Protestant world, and his Body of Divinity (1645) was Puritanism's earliest and most important volume of systematic theology. Ussher was born into a well-connected and highly-respected Dublin family in January 1581. His early education was supervised by two Scottish refugees, James Fullerton and James Hamilton, whose emphatic Calvinism had caused them to be driven from their native church. They exercised immense influence on their student, and, when Ussher entered Trinity College, Dublin, in 1593, one year after its opening, they were among the college's teaching staff. The atmosphere of the college was vigorously theological, with a strong bias towards Puritanism, and Fellows educated their students within the parameters of Reformed orthodoxy. Ussher made rapid progress.