As with all poetic interpretations and understandings, I think that one can find different answers to the question and it's important to make sure that all poetry is understood and reinterpreted on a personal level. With this in mind, I think that six sentences on Whitman's poem and Transcendentalism can look similar to this:
1) The Transcendental theme of self- wisdom can be seen when the speaker leaves the classroom to understand the natural world of astronomy through a subjective focus.
2) The Transcendental idea of individuality is evident when the speaker does not need to fully listen to the speaker, but rather finds an individual path to follow.
3) The Transcendental belief of non- conformity is evident when the rest of the class stays and the speaker leaves the classroom setting.
4) There is an emotional understanding of the world in Transcendentalism and this is evident in how the speaker of the poem interprets content through an emotional frame of reference.
5) The beauty and glory of the natural world as something that is part of the Transcendental movement is also present in the poem, where wonderment is evident in the natural beholding of it.
6) The devaluing of science, a major part of the Transcendental movement, is evident in the poem, where a major theme is that individuals do not need formal scientific processes to appreciate the beauty in the world.
We can, perhaps, also add the following:
1. Transcendentalism was a reaction to intellectualism in mid-19th-century America. This mode of intellectualism was heavily indebted to the Scientific Revolution and Enlightenment ideas from Europe, both of which elevated reason. One could read Whitman's reference to the "learn'd astronomer" as slightly derisive, for his learning about the stars has nothing to do with the stars at all, but is instead a matter of "proofs . . . figures . . . charts and diagrams."
2. The "emotional understanding of the world" which the previous educator mentions is derived from the Transcendentalist's connection to the Romantic movement. Insight mattered more than logic. The astronomer's careful scientific processes are contrasted with the narrator's wandering into "the mystical moist night-air." The lecturing is contrasted with the "perfect silence" of the night under the stars.
3. The Transcendentalists also eschewed authority, which is why Whitman's narrator spurns the astronomer's lecture and why the "applause" results in his "[becoming] tired and sick." The conclusion to draw here is that the lecturer has no more authority to tell us about the stars than we are capable of understanding them on our own by wandering off by ourselves to gaze at them. The phrase "from time to time" in the final line refers not only to the narrator's sporadic gazing but also to the ancient presence of the stars.