What is the emotional contrast between the sailor and the people on the dock and what point is Whitman trying to emphasize by presenting this contrast?

The sailor is filled with excitement and adventure, while the people on the dock are wistful and nostalgic. Whitman emphasizes the contrast to show the different perspectives people have on departing and arriving — the sailor sees opportunity and new beginnings, while those left behind experience longing and reflection. This highlights the cyclical nature of life and the contrasting emotions associated with beginnings and endings.