Any question that is asking about "transcendental identity" is asking you to explore the ideas of transcendentalism in a specific poem. In this case, the poem "Song of Myself" is the subject of the question. You are being asked to identify elements of transcendentalism in the poem. In other words, what examples of Transcendentalism does the speaker, presumably Whitman, address in the poem? When he talks about himself in the poem, where are there aspects of Transcendentalism? You will need to identify specific themes of the movement and examine the poem for lines where you see these themes. For example, where do you see an emphasis on the subjective self in the poem? When Whitman talks about his own sense of self, how is this reflective of Transcendentalist ideas? You will need to identify lines that support this. It is here where Transcendental identity becomes evident and here where your exploration is required. A line that could be used in this process would be something that talks about Whitman's beliefs and how these beliefs are a part of his identity. Linking this to Transcendentalism becomes a major part of this question.