In the poem, the speaker describes how she was "climbing up a mountain-path" when she came across "a Prejudice" blocking her path. This "Prejudice" is described with diction, and the poet uses words such as as hulking, colossal, and obdurate. Such diction emphasizes how impassable the "Prejudice" seemed to be. The speaker tries many ways to get around the Prejudice, but all are unsuccessful. Then she has "a sudden inspiration" and realizes that she can simply walk "directly through him, / As if he wasn't there!" The simple meaning of the poem is that prejudices only affect us if we allow them to.
The physical, corporeal "Prejudice" blocking the speaker's path is a metaphor for all of the intangible prejudices that exist everywhere in the minds of people. By presenting these intangible prejudices in the metaphorical form of a gigantic, unresponsive rock or creature, the poet can convey visually to the reader the idea that prejudices are obstructive and obdurate.
There are also similes in the poem that help the poet to convey how irrational prejudices are. In the fourth stanza, the poet says that she argued "like a Solomon" with the "Prejudice" and that still it "sat there like a fool." The first simile whereby the speaker compares herself to Solomon is also a biblical allusion. In the Bible, King Solomon is a very wise king, and so the implication of this allusion is that the speaker argued wisely with the "Prejudice." In the second simile, the speaker says that even though she argued wisely with the "Prejudice," it simply "sat there like a fool." This second simile emphasizes the point that prejudices are irrational and foolish. They do not respond to reason.
Throughout the poem, the poet uses syntax to further emphasize just how irrational prejudices are. Syntax refers to the order of words within a sentence. In a number of sentences in the poem, the poet follows a verb with a post-modifying adverb. For example, when the speaker says that she "spoke" to the Prejudice "politely," the post-modifying adverb "politely" indicates exactly how the speaker "spoke." Likewise when the speaker says that she "reasoned" with the Prejudice "quietly," the post-modifying adverb "quietly" indicates exactly how the speaker "reasoned." Both of these post-modifying adverbs emphasize how calmly and logically the speaker was when she tried to reason with the Prejudice and, thus, how irrational and unresponsive the Prejudice was in turn.