Causation is a key concept when we talk not only about events, but also about actions. Once a person has done something, his action results in further consequences up to nature. But even these consequences are often characterized as his actions, for example Kennedy's death which had causally resulted from the shooter's pulling the trigger also turned to the shooter's action, viz. his killing Kennedy. Thus we can find development of actions along with a causal chain. First we show that such development of actions, which is so called accordion effect,'is specific to the way of our talking about actions. In short accordion effect gives us a clue to distinguish human actions from mere events. And the rest of this paper is devoted, to establishing the grammar of accordion effect. Through our considerations we will be able to reach a better understanding of the concept of action.