I recently read the Hitler Salute: On The Meaning of a Gesture by Tilman Allert. This book explained the compulsory nature, pervasiveness and significance of the Hitler salute.
As Professor Allert writes, "With the Hitler salute, the regime intruded into the tiniest elements of everyday life. Postmen used the greeting when they knocked on people's doors to deliver packages or letters. Customers entering department stores were greeted with "Heil Hitler, how may I help you?" In no area of their lives were Germans exempted from the duty to perform this 'bit of practical National Socialism'. Everywhere throughout Germany, small metal signs reminding people to use the Hitler salute were posted in public squares, on telephone poles and street lanterns. The greeting became a component of academic rituals from the university down to kindergarten, a compulsory framework for the pedagogical relationship. Kindergarten and primary school teachers had their pupils say the new greeting over and over until they got right. Pupils were required to say 'Heil Hitler!' at the beginning and end of every school period, and the first thing each new class of first graders encountered when they opened their primers was a lesson on how to greet others, replete with people lining the streets, their arms raised in the Hitler salute."
The Hitler Salute presents a great case on the disproportionate impact of small gestures. Other examples of seemingly small occurrences impacting world events are presented in The Power of Incremental Advantage: How Incremental Improvements Produce Dramatically Disproportionate Results.
