From Chapter 1 of Make Yourself Clear:
A seesaw is not really a game. It is more of a preoccupation, wherein both parties concentrate on the action, engrossed for as long as it holds their attention. While the board is in motion, there is no end and no beginning. When one person decides to stop – sometimes by rudely jumping off and sending the other person plummeting toward the dirt – the preoccupation ends. For the game to continue, both players have to be mutually invested in the outcome – and each other.