His manner made it impossible for Arthur to persist.

For Dory was one of those who have the look of "peace with honor" that keeps to bounds even the man crazed by anger.
"You can't deny I have a legal right to make the contest," pursued Arthur.
"Undoubtedly." "And a moral right, too," said Arthur, somewhat defiantly.
"Yes," assented Dory.

The tone of the "yes"-- or was it Arthur's own self-respect--made him suspect Dory of thinking that a man might have the clearest legal and moral right and still not be able to get his honor's consent.

"But why discuss the matter, Arthur?
You couldn't be changed by anything I'd say." "We will discuss it!" exclaimed Arthur furiously.

"I see what your plan is.