Can anyone identify a story for me?

I read this poem or story in junior high school in an anthology.  It has always been influential on me, but I can't find it.  The poem or story describes two  men, one black, one white, who approach each other on a  road.  The white man displays ignorance, the black man remains composed, rational, and immune to the ignorant insults.  Like a Black Vulcan:  "Well you a n----- ain't you?"  "My ancestors were called by that word."  "And you can't marry my sister!"  "Having never met your sister, I don't feel deprived by that."

The story taught me at age 12 that an ignorant person can't define me, they can only define themselves.  That idea has always immunized me from psychological attack.