Throughout the late Middle Ages and the early modern period, the Low Countries were home to a vibrant tradition of lay philosophy in Dutch. Sparks of Reason takes a detailed look at this philosophical tradition, with a special focus on the sixteenth century. During this turbulent century, several authors, such as Dirck Volkertsz Coornhert (1522-1590) and Hendrik Laurensz Spiegel (1549-1612), developed a philosophy which was founded on rationality and self-motivation. This “Vernacular Rationalism” was a dynamic melting pot of classical philosophy, Humanism, Spiritualism and popular piety. As this book shows, Vernacular Rationalism was rooted in an age-old Netherlandish tradition and was to become one of the breeding grounds for the Early Enlightenment in the seventeenth-century Dutch Republic. Its point of departure was the inherent goodness of humankind and the possibility of moral growth through rational knowledge. Its goal was perfect happiness.