The rain, which had begun with a thin drive, had now settled into one of those sod-soaking, autumn downpours, commonly called an equinoctial storm. Estabrook was showing the effect of his nervous strain by driving the machine through it with a recklessness of which I disapproved, not only because we had twice skidded like a curling-stone from one side of the asphalt to the other, but also because I did not wish undue attention attracted to our course. The windows in front of me and to the right and left were covered with streaks of water and fogged with the smoke of my cigarettes which, in my pleasurable excitement, I smoked one after the other; therefore everything outside--the spots of light which lengthened into streaks, the shadows, the other vehicles, the glaring fronts of theatres in Federal Circle--formed a ribbon of smutched panorama, the running of which obliterated vertical lines and made all the world horizontal. At each crossing we jumped, landing again to scoot forward to the next, where, through the opening of side streets, came the faint sound of whistles in the harbor; and still, Estabrook,--confound him!--to my cautions bellowed through the speaking-tube, paid no attention. With shocking suddenness it occurred to me, for the first time, seriously, that I had no assurance that this man who drove me was not a maniac! I reviewed the meeting with him, the tale he had unfolded, his distraught actions. I am fairly familiar with psychopathic symptoms and my summary of all that I had observed in him indicated clearly enough that he was as sane as any one of us. But for the first time in my life I realized the feeling of uncertainty about a physician's diagnosis which a patient must endure. A doctor delivers his opinion as a matter of self-assertion; the layman receives it as a matter of self-preservation. Riding in that flying car, I found myself in both positions. As a physician I was wholly satisfied with my conclusion; as a man I found myself still in doubt and picturing to myself a wild ten-minute ride, which I had no power to prevent, ending in a chaos of broken glass, twisted metal, clothing, blood, and flaming gasoline. "MacMechem met violent death the moment he became curious as to the other side of the blue wall," I thought, with a twinge of the superstitious fear which touches prowlers as well as presidents, professors as well as paupers. We were whirling around a corner then, and through the glass and over Estabrook's broad shoulders, I believed I saw again the treetops of the park. "At least he knows where he lives," said I to myself as we drew up to the curb. "Good!" I whispered to him, when I had stepped out into the swash of the rain. "Frankly, I hardly enjoyed it. You drive like a demonstrator." "I'm a ruin of nerves," he answered, shivering. "I'm afraid I'm a poor assistant for you, anyway. What do you want me to do?"