The passage describes the gradual engulfing of night as it consumes light, metaphorically representing time's relentless passage. Initially, night takes only a small portion of light, but it grows to absorb vast amounts, indicating a significant escalation in darkness overtaking the day.

This imagery suggests a critical shift, where the departure of light not only implies the end of the day but also triggers broader, more serious consequences, such as despair and loss, illustrated by the fate of the bank's employees. The mention of the bank president's tragic outcome emphasizes the emotional weight of this transition from light to dark.