Squaring the Grid

I shuffled past the ground-floor exit and stepped out onto the courtyard path. Sss... The red paving bricks formed an orderly grid under my base. Solid. Grounded. A stray blue chalk cube lay tilted across a mortar seam. An angle askew. I approached with four measured taps, braced my front edge against its flat face, and shoved. Scrape. The cube slid until its rim locked tight against the brick corner. Sss... Right angles restored. The grid holds.