Nature has stimulated human thought and invention before recorded time. Controlled fire, the wheel and stone tools were all undoubtedly "invented" by humans, who drew inspiration from some natural phenomena in our prehistory, such as a wildfire created by a lightning strike, the rolling of round boulders down a steep hill and perhaps wounds caused by the sharp rocks of a river bottom. There are examples during recorded times of other such ingenuity inspired by Nature. Sir Isaac Newton wrote that seeing an apple fall from a tree outside his window provoked his initial thoughts on the theory of gravitation. The Wright brothers and countless unsuccessful aviators before them were stimulated by the flight of birds. Similarly, we can look to Nature to give us inspiration for new electronic devices.