plain, your express is between A, B and I. That is certain…'
"'But!'
"'Hush! Be quiet! And since we are in a plain, and in that plain there is an immense mass of loose sand, the only place in which the train could have disappeared is in that mass of sand: that is the eternal truth!'…
"'I swear it didn't! I was at K waiting for the express; and I did not quit the line H I.'
"'By the immortal Masterpieces of the Italian Renaissance I command you not to let go of the right end of your Reason which I have put into your hand. We are discussing at this moment what is; we are not yet at the how. It is owing to the fact that you began with the how that you have not been able to reach what is. The express is in I, since it cannot be anywhere else. I am sure that the five men could not have seen it pass B, as they assert, unless it had passed. I am as certain that five men could not have been unable to see it at A if it had passed A; and since the line A B was examined and found not to contain the express, it must be that it turned off up the line H I. There we are, then, with the train on the line H I.'
