What makes a movement take off? Is it the existence of a leader with the courage to stand up for a new idea? Derek Sivers argues that it's the first follower who makes the movement take off. Until then, the initiator just looks crazy. Sivers illustrated this with a cute video of a crazy guy dancing in a park. At least, he looked silly until the first person had the courage to join him dancing. Within minutes, the hill was crowded with dancing people.
Sivers is also responsible for another of my favourite short talks on TED.com, in which he talks about seeing the flip side. Americans name locations by street names, whereas Japanese name locations by the blocks. This can lead to puzzlement and it's an interesting way of explaining how cross-cultural communication can be derailed.
In my innovation courses, I hammer the necessity of questioning assumptions to have any hope of creative innovation. The hardest assumption to challenge is the one you don't know you're making. Sivers' talk does a great job of pointing out one assumption most of us have never questioned.