What image do we see in the first stanza of the poem?

In the first stanza, we see the effects of the wind in the trees. Although no one has ever seen the wind, the speaker says, we can see its effects all around us, especially in the trees. The speaker then personifies the trees as trembling in the wind, and the reader is granted a sense of the sublime: the wind, it seems, inspires awe and terror as it passes by, even in trees.