The news about how he lost his sight was sobering, but he didn't want to pry too deeply. The coincidence of giving the lecture before the event happening was too close, and made him wonder whether he would remember his time in Knowhere once he was returned.
It was much easier to discuss flora and interior decorating.
"Have you ever seen those fountains that move in sync with music and lights? I was thinking of bringing in one of those, but maybe not here. It would ruin the whole atmosphere. But maybe in one of the other rooms." He paused. "There's a chocolate mint plant?!"
As far as the Doctor was concerned, the discussion about the Monks and saving the Earth and his blindness was over. What mattered most to the Doctor was their relationship here and now.