The young man, probably a student, who wears a suit and reads a book, presages the "defiant, non-violent non-cooperation of the Civil Rights Movement" (enotes) as he declares, "We should question and question and question--question everything."
On the other hand, the preacher represents the status quo of the black of the era. He is appalled by the youth's disrespect, just shaking his head in bewilderment. But the youth continues to "rock that pillar" that the others lean on, he says. When the preacher hits him, the youth satirizes the Christianity of the minister by saying, "You forgot the other cheek," alluding to the New Testament verses in Matthew. He tells the people in the dental office "Words mean nothing. One means no more than the other." This is why he says the grass is black and the sky is pink--he wants people to question the existence of things, question the status quo. Why is it the way it is? Is it so for the same reasons that everyone agrees that the grass is green? Because they have been told it is green, they believe, the youth seems to imply. Of course, James does not understand all that happens, but he senses that the youth acts in an unconventional manner to stir others to think on situations and the time they live in.