The poem is a short, playful push toward leaving: choosing motion over staying put. The first stanza sets up a odd little argument. Summer has a "mad wisdom," and in that spirit, setting sail seems better than "a bad birth." The phrase is strange, and it can be read a few ways. Perhaps it means that starting something badly, or being stuck in a poor beginning, is worse than simply heading out and trusting the journey.
The second stanza turns to the road, which "takes notice of you." That small bit of personification makes travel feel like a relationship, as if the world pays attention once you start moving. The "Zen merchant singing / for the company" is a charming image: someone who sells things yet seems calm, unbothered, and cheerful, performing just to keep others company.
The speaker sounds light, curious, and a little mischievous. The mood is breezy and open, with a hint of gentle humor in the title's contrast to the quiet, unhurried voice inside the poem.