"'But I was there too,' cried Theophrastus, 'and I swear to you that it wasn't!'
"'Dear! Dear! Do hold on to the right end of your Reason! You were at K; the express passed K; it must pass K; it must go and plunge into I, since it cannot be anywhere else. By a necessary chance, while the beginning of the train is engulfed in the mass of sand (I take it for granted that the line H I is too short for the engine-driver, having perceived the error of direction half-way up it, to have had the time to ward off the catastrophe), the couplings of the last carriage broke, and the carriage and the guard's-van began to descend the line which was on a slope since it went to this mass of sand. There, after having gone down the line to H and back up it to K, you saw the carriage and Signor Petito at the window. (Probably Signor Petito opened the window with the intention of jumping out, at the moment he grasped the imminent catastrophe, and as it happened the shock of it shut his head in the window.)'
"'That I understand; but what I don't understand…'
"'Let us first consider what we do understand: that is the right end of Reason. We will next consider what we do not understand.
