If you live in a place with a 100,000 small birds population, you've certainly see strong patterns in the way they flight, in organized clusters and sub-clusters of 500 or 5,000. They go up or down, turn left of right, or accelerate or brake, all at the same time in a perfectly synchronized ballet.
You might ask yourself how can they accomplish this. Surely, they don't have a shared, well known flight path, as they turn every 5 seconds. So there must be a leader, and each bird follows someone just above her in the hierarchy. Sometimes though, something goes wrong, and the synchronization is lost: birds in a very large compact flock seem to suddenly be flying erratically, bumping against each other, as if they've lost control. This type of flight is very destructive and can result in a massive collapse.
Is there any analogy with the way the economy operates?