It's an urge that's existed probably as long as people have paced the earth.
Ancient scrolls talk about flying in religious tones.
Medieval times saw people jumping off towers and drawing fanciful flying machines. What most probably don't realize, however, is that Lilienthal's first aerodynamic concepts leaned heavily on bird flight. Lilienthal even went so far as to study each and every known bird, looking for relationships between wingspan and weight, and number of flaps versus distance of gliding flight. It wasn't until the Wright brothers came along that we first began to truly understand how to make an aircraft fly. As it turns out, nature does provide some aerodynamic guidelines and parallels, but flapping wings sure aren't one of them.