As symbolized by the swan’s quick motion over the water, change is inevitable. The swan cannot stay in one place; it floats along the eyeline or rises from the water in a flutter of wings. The poem’s call-and-response technique shows that the swan’s arrival is highly anticipated: “When Soon before its shadow fades” (Line 11). However, the swan’s arrival itself foreshadows its departure. The speaker is aware of this inevitability, realizing that the swan will appear moments before its shadow dissolves.

In Line 18, the poem emphasizes the present moment: “[E]ven after this bird this hour both drift by atop the perfect sad instant now.” The swan and the hour both pass; they cannot be stopped. The “now” is perfect, yet “instant” and “sad”; “instant” because it exists only in the experienced moment and “sad” because the present moment is always lost (Line 18). Thus, the poem expresses its deep, metaphysical engagement with the nature of change. People dread change, yet change is the only constant in life because of the nature of existence.

However, the swan’s passage is not entirely pessimistic. The swan is a harbinger of change: The scene before its arrival and the scene after its departure are not the same.