How does this contrast reveal the poem's theme its central insight into relationship between human and nature?

Question

The poem of tide rises the tide falls

Answer 1

The Tide Rises, The Tide Falls
Henry Wadsworth Longfellow
The tide rises, the tide falls,
The twilight darkens, the curlew calls;
Along the sea-sands damp and brown
The traveler hastens toward the town,
And the tide rises, the tide falls.
Darkness settles on roofs and walls,
But the sea, the sea in darkness calls;
The little waves, with their soft, white hands
Efface the footprints in the sands,
And the tide rises, the tide falls.
The morning breaks; the steeds in their stalls
Stamp and neigh, as the hostler calls;
The day returns, but nevermore
Returns the traveler to the shore.
And the tide rises, the tide falls.

Analysis:
Invoking the elements of popular romanticism that was popular in many writers' works of the time period in which the poem was written, Longfellow portrays death as a fact of life,an inevitable occurence to be accepted, but not feared. The symbolic nature of the tides suggest that death, like the ocean, is ceaseless, and forever. Just as one cannot stop the tides of the ocean erasing their "footprints in the sands", or rather their existence in the world, one cannot stop death from claiming his/her life.