The outer and inner Journeys comprise the two most important strands of a story, which is another way of saying that they relate how the hero acts in the world, and why.
The outer journey, we are reminded, recounts, beat-by-beat, the external events of the Hero struggling against mounting obstacles to achieve the visible goal of the story—preventing the bomb from going off, winning the race, preventing a robbery, and so on.
The inner journey, by contrast, is the internal path the Hero takes to enlightenment as he initiates or reacts to the outer journey’s challenges, surprises, and setbacks.
“The pivot points merge the story strands, the outer and inner events of the tale, into single actions.”
Lagos Egri, one of the most lucid teachers on the craft of dramatic writing, explains that the inner journey is the “why” to the outer journey’s “what”. In short, the turning points, including your midpoint, describe events that cause the Hero to react in a way that is in keeping with his evolving inner state.
Is it preferable to let the inner state, or, journey, trigger the outer event, or should it be the other way around? There is probably no definitive answer to that question—either will do, as long as both through-lines are tightly interwoven.
In Rob Roy, Liam Neeson’s character accepts his wife’s unborn child—a result of her being raped by an Englishman, because of who he is: a man of immense conviction and inner strength. He manages to kill the fop, an expert English swordsman, despite his being defeated in the actual sword fight, because of this inner strength and conviction.
In Breaveheart, William Wallace accepts his knighthood at the midpoint of the story. This motivates him to move from being an isolationist who merely wants to be left alone to farm with his family, to a national leader who takes up arms against the English. The ceremony is a perfect fusion of an outer and inner event—as a knight he now has a moral obligation to fight for those who fall under his protection.
The pivot points are the perfect place for the story strands to merge and ensure that the “why” explains the “what” in the story.