Step, leap

Aliyah walks toward one side of a half-meter-wide ditch. Without missing a beat, she plants her left foot at the rounded lip of the ditch and then swings her right leg forward over the ditch to plant her right foot at the opposite lip, bobbling her upper body forward in dynamic equilibrium between the upward-centerward forces from her proceeding alternating legs, in a smooth motion reprising her past steps over solid ground.

Boaz, following Aliyah, walks toward the half-meter-wide ditch. He starts to step across, but pauses halfway through, poised over the ditch. To amuse himself, he reverses by pushing back on the opposite lip, starts forward again, goes almost all the way, then reverses again. With just a bit of effort he can statically occupy a near approximation of any position and stance that Aliyah passed through during her step, dwelling for a time in that moment that was for Aliyah a non-extended point in a dynamic process.

Carmel walks toward a meter-wide ditch. A push from her left foot, a split second before her right foot touches the opposite lip, propels her across, an instant of falling bracketed on the beforeside by a pistoning-tipping-unpistoning left leg and on the afterside by a pistoning-untipping-unpistoning right leg.

David, following Carmel, pauses like Boaz over the meter-wide ditch, trying to recreate Carmel's big step as a sequence of still moments. In a few minutes of trying, he doesn't do it. He can stop in mid step and reverse, and he can reproduce Carmel's stance on the beforeside and on the afterside. But there is a region in the process of Carmel's step, surrounding the moment when she was falling, where David can't stay still. David can position his torso statically at any point along the trajectory of Carmel's torso, and he can even with some effort construct a series of individually stable stances that take his torso along the trajectory. But he doesn't quite succeed at making a motion that can be reversed and could at any point be a stable stance; in reaching his foot across the ditch, especially backward, there's always a moment where he starts to tip over until the foot makes contact. And anyway, in those attempts, the positions of David's body as a whole are unlike the positions of Carmel's body as whole.

Eva comes to the lip of a meter-and-a-half-wide ditch. She wants to keep her feet under her, so she cautiously stretches her right foot across, and then lets her torso tip forward, and unpistoning her left leg, she catches her right foot on the afterside lip. She's stuck! With her legs at too obtuse an angle, both extended so that pistoning one would require her to sink even lower, she can't push forward, nor push back to the beforeside. By lowering her torso, barely able to support herself, Eva can piston her left leg just a little and push off. Crouching forward, she has just enough momentum to keep her body out of the ditch, though she has to drag her left leg up out of the ditch against the afterside lip.

Feivel pauses at the lip of the meter-and-a-half-wide ditch, feet together. In one quick motion he jumps, barely making it, almost overbalancing backwards.

Galit clears a two-meter-wide ditch with a running leap.