The role of "incidents" can thus be seen as a coordinating role; it is a substitute for overt leadership and communication. Without something like an incident, it may be difficult to get action at all, since immunity requires that all know when to act together. Similarly, the city that provides no "obvious" central point or dramatic site may be one in which mobs find it difficult to congregate spontaneously; there is no place so "obvious" that it is evident to everyone that it is obvious to everyone else.

Thomas C. Schelling, The Strategy of Conflict, loc. 220