"Oh, I am careful, Harriet; Dr. Sinclair allows me to move a little.... Mr. Eaton, in one of the three answers you have just given me, you are not telling the truth. I defy you to find in human reasoning more than four reasons why my presence could have made you take this train in the manner and with the attending circumstances you did. You took it to injure me, or to protect me from injury; to learn something from me, or to inform me of something. I discard the second of these possibilities because you asked for a berth in another car and for other reasons which make it impossible. However, I will ask it of you. Did you take the train to protect me from injury?"
"No."
"Which of your former answers do you wish to change, then?"
"None."
"You deny all four possibilities?"
"Yes."
"Then you are using denial only to hide the fact, whatever it may be; and of the four possibilities I am obliged to select the first as the most likely."
"You mean that I attacked you?"
"That is not what I said. I said you must have taken the train to injure me, but that does not mean necessarily that it was to attack me with your own hand. Any attack aimed against me would be likely to have several agents. There would be somewhere, probably, a distant brain that had planned it; there would be an intelligent brain near by to oversee it; and there would be a strong hand to perform it. The overseeing brain and the performing hand—or hands—might belong to one person, or to two, or more. How many there were I cannot now determine, since people were allowed to get off the train. The conductor and Avery—"
"Father!"