Whitman immediately indicates his intention right from the first stanza when he addresses the people and tells them that they are more curious to me than you suppose. He proceeds to mention how a simple, compact, well-joined scheme connects the past and the future like beads. This theme of oneness would then be emphasized and reiterated in the succeeding lines as the poet proceeds to describe the various sights and sounds that one would sense as a passenger of the ferry, each one acting as symbols to support the poems theme.
He describes the experience of watching the seagulls in the sky, being dazzled by the glare of the sun, the ships of all varieties and sizes both anchored and sailing, and even the chimneys and the lights from the buildings by the shore. The profusion of images and repetitions in sentence structure create a sense of wholeness to the world being described by the poet. This emphasizes to the reader that the ferry ride is a symbol of the totality of the life experience and connectedness of the past to the future not just for one person, too, but for others as well as Whitman states that These, and all else, were to me as they are to you.
The entire poem is full of activity but this sense of constant movement effectively conveys the continuity of everything in life that the poet wants to describe. There might be changes like new buildings rising, but change is also part of this chain of movement. The immortality of humanity lies upon the fact that we do not cease to exist, generations succeed one after the other, and natural elements like the sun and tides keep their regular patterns.