 The Enlightenment was a reaction to the rise and successes of modern science in the sixteenth and seventeenth centuries. The spectacular achievements of Newton in particular engendered widespread confidence and optimism about the power of human reason to control nature and to improve human life. One effect of this new confidence in reason was that traditional authorities were increasingly questioned. Why should we need political or religious authorities to tell us how to live or what to believe, if each of us has the capacity to figure these things out for ourselves? Kant expresses this Enlightenment commitment to the sovereignty of reason in the Critique: