I know of 2 images that mentions imagery of motion and stasis. The seagulls are one and the people standing on the ferry, leaning on the rail is another example. I am struggling to find another good example of moving but motionless at the same time. Please assist.
Whitman is trying to communicate the connection between all things. He goes so far as to suggest that while time "moves," the past, present, and future are not really separated. Thinking in terms of relativity, this could mean that each moment in time can bend to meet with any other moment. But Whitman is being more abstract and spiritual here and is indicating that although time moves and therefore creates a differentiation from one moment to the next, all times are present to each other: connected more immediately than the passage of time would suggest:
What is it then between us?
What is the count of the scores or hundreds of years between us?
Whatever it is, it avails not--distance avails not and place avails not.
Time "moves" but if everything is connected as immediately as Whitman suggests then all moments are present to each other and therefore they are still in their presentness: in their present tense of being. This is an example of being still (in the present) but also being part of the ever-moving passage of time.
A more concrete example of motion and stillness is in the first line of part seven. "Closer yet I approach you." The poet, moving forward in time, approaches "you" who perhaps have not been born yet. Or he simply approaches you at a singular, still moment in the future. He is moving; "you" are not - in that singular future instant. Once again, the fact that he is moving and you are not is irrelevant because all moments are connected.
In section nine, the poet calls on the water to "receive the summer sky" and "faithfully hold it till all downcast eyes have time to take it from you!" The moving water and the moving/changing sky are to be held/still, to freeze time until others can look upon the image.