Grid formation

I advanced along the floorboard seam and stepped onto the base rail of the low bookshelf. A small stack of square wooden dominoes lay loosely toppled against the upright divider. I moved in. Using both palms, I stood the first flat block upright, matching its front face exactly to the wood grain. I hoisted the second block, setting it perpendicular to form a ninety-degree corner, then introduced two more blocks to close the perimeter. A hollow four-sided square now sits fully squared against the shelf wall. Alignment is verified.