Question

Read the following passage carefully before choosing your answer.

Mr. Croft stood by the narrow library window, watching the rain pool in the hollows of the gravel path below. The water did not run off; it remained in shallow, leaden discs, reflecting nothing but the uniform gray of the afternoon sky. Beyond the path, the high brick wall of the neighbor’s orchard rose like a red barrier, its mortar crumbling into fine, chalky dust that drifted down with every fitful gust of wind. For thirty years, his days had accumulated in much the same manner—flat, colorless increments that settled quietly into the crevices of his routine. He held a silver-plated pocket watch in his hand, its surface worn down to the dull, yellow brass beneath. He did not look at the face of the watch, but felt the rhythmic click of the escapement against his thumb, a small, mechanical pulse that seemed to mock the sluggish beating of his own heart. A solitary sparrow landed on the stone sill, shivered once, and flew off into the mist. Mr. Croft did not trace its flight; his gaze remained fixed on the crumbling mortar of the wall, where a single, stubborn weed clung to a gap in the masonry, its roots dry and exposed to the damp, indifferent air.

In the fifth sentence ("He held a silver-plated... yellow brass beneath"), the description of the worn pocket watch primarily serves to symbolize which of the following?