have one's doubts

As to that foreign Marchioness, of whom it is well to have one's doubts, if it becomes advisable to get rid of her, her handsome head with its black hair will look well on the end of a pike some of these days.

To have one's doubts, one's misgivings, one's own blank confusion portrayed with such appreciation and in such vivid detail by another—how could it fail to powerfully affect me?