What phrase does the narrator ue to describe Dr. Bledsoe's position relative to the trustees around him? why is this significant?

"I watched him smiling at first one and then another of the guests, of whom all but one were white; and as I saw him placing his hand upon their arms, touching their backs, whispering to a tall angular-faced trustee who in turn touched his arm familiarly, I felt a shudder. I too had touched a white man today and I felt that it had been disastrous, and I realized then that he was the only one of us whom I knew -- except perhaps a barber or a nursemaid -- who could touch a white man with impunity."

Dr. Bledsoe's position seems natural. This is significant because the narrator is beginning to understand that touching a white man or being respected by a white man was attainable. Rare...... but attainable.