Moshe establishes the Jewish people as G-d’s exclusive nation, and is not limited to those present on that day, but includes all future generations (29:14). How can future generations be bound by a covenant they were not present to accept?
Rabbi Jonathan Sacks suggests that just like being born into our families is not our choice, we are still affected by what has come before us, and it is that which becomes part of our history and who we are. Just like the past influenced who we are, our actions determine what happens beyond us. While future generations don’t get to choose the world they’ve inherited, they will get to leave their mark in what their future will see as the history of that world. We are part of the Jewish “his-story”; our choices and what we choose to make of our chapter will determine the future of our personal story.