The narrator finds the scene with the blond man in "The Prologue" of Invisible Man ironic because the man has been "mugged" by someone who is "invisible."

In "The Prologue," Ellison's narrator explains his theory of invisibility. He says he is not literally invisible; rather, he is not seen by others. He writes, "I am invisible, understand, simply because people refuse me" (3). The narrator relates the encounter with the blond man, saying he "accidentally bumped into a man," who then called him a racial slur. He insisted the man apologize to him, but he would not, so the narrator beat him bloody. The irony of the encounter is described as follows:

it occurred to me that the man had not seen me, actually; that he, as far as he knew, was in the midst of a walking nightmare! . . . I was amused. Something in this man's thick head had sprung out and beaten him within an inch of his life. I began to laugh at this crazy discovery . . . The next day I saw his picture in the Daily News, beneath a caption stating that he had been "mugged." Poor fool, poor blind fool, I thought, with sincere compassion, mugged by an invisible man! (4-5).

In this passage, the narrator highlights how the man does not see him for who he truly his, as indicated by his use of slur. The blond man does not view the narrator as a human being equal to himself. Therefore, the narrator theorizes that he is invisible to this man and laughs at the absurdity that someone/something that isn't actually there could attack this man. Of course, the narrator attacks the man because the man does not truly see him.

This anecdote is one of the centerpieces of "The Prologue," in which the narrator introduces this theory of invisibility. He then goes back and tells the story of his life, of the events that led him to surmise that he is not seen by others.

The irony here is that, although the blond man may not have been able to see the narrator, society has. What's more, they've only seen him in the guise of a mugger, a common criminal, rather than acknowledging his humanity. This will be a perennial problem for the narrator throughout the book.

It also illustrates the limitations of his grandfather's recommended strategy of keeping your head down and adopting a meek posture in relation to white folk: that's precisely what the narrator has been doing, but it clearly hasn't done him any favors. He's come to realize that his invisibility in society comes and goes and is determined at any given time by the dominant white man. This leads him down a path that will involve rejecting his grandfather's well-meaning but ultimately ineffectual advice.

This encounter, which occurs in the Prologue of this novel, is important because it introduces important themes and concepts that govern the rest of the novel. Let us remember what happens: the narrator bumps into a...