A movement in the space-time continuum represents (ultimately) a negation. The positive cancels other possibilities. The positive is the concrete that fills the void of the possible.
If I move my hand to select an item from a shelf, I am negating all of the other items I may have selected instead. I am negating all of the other movements I might have made instead of selecting anything. I am negating a myriad of possibilities. Sartre understood the power of negation as it relates to the positive, but I see negation as directly connected to the termination of possibilities.
If I had a large house with many items burning to the ground, imagine I am only able to rush in and bring just one out. That particular item serves as an indicator as to who I am and what matters to me. Its power is not derived only from what it is, but rather from what it is not. What about the other 10,000 items I abandoned? If I had $50,000 hidden in the closet but a photograph of my child on the borough, and if I choose the photograph over the money, what does that say about me? Not choosing the $50,000 tells me more about the photograph. It provides additional information. The myriad of negations in my life, the elimination of possibilities in favor of what I move from possible to actual, is a profound indication of my essence.