"I was also painfully conscious of the fact that, while I must be true to my own race in the utterances, I had it in my power to make such an ill-timed address as would result in preventing any similar invitation being extended to a black man again for years to come."
page 143

I took this quote as saying that he would like to speak out against what slavery was, but felt that if he wanted to appeal to the audience and help out blacks in the future, he would have to limit what he said. I think that, like we said in class, he didn't want to get himself in a bad situation so told people what they wanted to hear rather than how he really felt.