That's right, wisdom and knowledge, for the two are not the same thing. Wisdom is gained through experience and activity, such as the exploration of nature. Knowledge, by contrast, is gained through culture. A geometry equation could be knowledge, but it's not wisdom. Same goes for the discovery of the elliptical orbits of the planets. In "When I Heard the Learn'd Astronomer," Whitman turns away from knowledge in favor of wisdom, which he views to be as sudden and spontaneous as an intuition. The speaker's silence at the end of the poem is the strongest evidence of his wisdom, following the old saying, "Those who don't know, talk. Those who don't talk, know."
The poem argues that true wisdom is a form of childlike play.
The poem manifests the transcendentalist idea that true reality is a unified substance behind the diverse forms of the external world.