He nodded, and we were both silent for a while.

“The probability,” he resumed after a pause, “that Mr. Graves is alive at this moment seems to me infinitesimal. There was evidently a conspiracy to murder him, and the deliberate, persistent manner in which that object was being pursued points to a very strong and definite motive. Then the tactics adopted point to considerable forethought and judgment. They are not the tactics of a fool or an ignoramus. We may criticize the closed carriage as a tactical mistake, calculated to arouse suspicion, but we have to weigh it against its alternative.”

“What is that?”