I am the teacher of athletes,
He that by me spreads a wider breast than my own proves
The width of my own,
He most honors my style who learns under it to destroy the
Teacher.

from Walt Whitman – Song of Myself on Rap Genius

Meaning

He’s saying that his wisdom is only as valuable as its ability to teach.

He is teaching to others, and countless poets and writers in subsequent American and world literature will take up his challenge. William Carlos Williams, Jorge Luis Borges, Pablo Neruda, Hart Crane, Langston Hughes, and Allen Ginsberg are just a handful of poets on whom Whitman had a major influence, and his presence can be felt more subtly in writers as diverse as Marianne Moore, Wallace Stevens, John Ashbery, and Jorie Graham.

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