The enlightenment happened for the same reason that the renaissance happened. Exploration and introduction to new lands, knowledge, goods, wealth, etc. The renaissance was the result of western europe's direct connection to east ( china, india, etc ) via the mongol empire in the 1200s. The enlightenment is the result of western europe's direct connection to the americas via columbus in the late 1400s. It's not an accident that most scholars use 1500 as the boundary between the renaissance and the enlightenment.