Whitman’s poetry is generally classified as part of the Romantic school. The Romantics were to a large degree anti-science, anti-reason, anti-logic. In fact, the German Romantic poet Novalis said: “Poetry heals the wounds inflicted by reason.” The Romantics valued emotion, feeling, instinct, belief, love, unmediated interactions with life. They saw science trying to turn everything into formulae, to dissect, to impose order, to explain when no explanations were necessary. The learn’d astronomer sees the stars and thinks, How, Why, Where, How much, How can this be explained and predicted, How can this be quantified? Whitman and the Romantics were saying STFU and just enjoy the beauty, feel the power.

When I Heard the Learn’d Poet
by Scott Aaronson

When I heard the learn’d poet,
When the Freudian symbolism, the Biblical allusions, were ranged in columns before me,
When I was shown the themes and styles, to analyze, categorize,
and criticize them,
When I sitting heard the poet where she lectured
with much applause in the lecture-room,
How soon unaccountable I became tired and sick,
Till rising and gliding out I wander’d off by myself,
In the rational dry night-air, and dropped my copy of Leaves of Grass off a cliff,
And correctly predicted that it would hit the ground in 3.82 seconds.

[Taken from : http://www.scottaaronson.com/writings/whitman.html