Tread Pattern

The slatted shelf was conquered. My eyes were on the floor. I dropped down from the lowest rung and hit the woven carpet flat-footed. A discarded black rubber sneaker stood right in my path, massive as a boulder. I didn't walk around it. I stepped straight into the arch and wedged my shoulder against the rubber wall to test the give. Tough synthetic grip. Along the outer heel, tiny triangular tread markers formed a rigid diagonal chain. I traced the pattern with my thumb. Flawless traction. The floor is vast, but this terrain yields to steady footing.