But he makes a sudden doubt invade the Pope with a chill.

Has he judged rightly in thinking that divine truth is with him?
Is there any divine truth on which he may infallibly repose?
And then for many pages we are borne away into a theological discussion, which I take leave to say is wearisome; and which, after all, lands the Pope exactly at the point from which he set out--a conclusion at which, as we could have told him beforehand, he would be certain to arrive.

We might have been spared this.

It is an instance of Browning's pleasure in intellectual discourse which had, as I have said, such sad results on his imaginative work.

However, at the end, the Pope resumes his interest in human life.