Accordingly I devoted the following day to meditating my plan of attack, for I felt that I had been challenged to a final contest. Late the next day, I felt confident of my own ability to dispossess him, and in order further to test his power, when night came I doubly locked the door to my room, first with the key and next with the inside bolt. I had determined to force him again to induce inert material to obey his command, as he had done at our first interview. The reader will remember that Prof. Chickering had deemed that occurrence an illusion, and I confess that time had dimmed the vividness of the scene in my own mind. Hence I proposed to verify the matter. Therefore, at the approach of nine o'clock, the evening following, I sat with my gaze riveted on the bolt of the door, determined not to answer his knock. He gave me no chance to neglect a response to his rap. Exactly at the stroke of nine the door swung noiselessly on its hinges, the wizard entered, and the door closed again. The bolt had not moved, the knob did not turn. The bar passed through the catch and back to its seat,--I sprung from my chair, and excitedly and rudely rushed past my guest. I grasped the knob, wrenched it with all my might. Vainly; the door was locked, the bolt was fastened. Then I turned to my visitor. He was quietly seated in his accustomed place, and apparently failed to notice my discomposure, although he must have realized that he had withstood my first test. This pronounced defeat, at the very beginning of our proposed contest, produced a depressing effect; nevertheless I made an effort at self-control, and seating myself opposite, looked my antagonist in the face. Calm, dignified, with the brow of a philosopher, and the countenance of a philanthropist, a perfect type of the exquisite gentleman, and the cultured scholar, my guest, as serene and complacent as though, instead of an intruder, he were an invited participant of the comforts of my fireside, or even the host himself, laid his hat upon the table, stroked his silvery, translucent beard, and said: "Well?" I accepted the challenge, for the word, as he emphasized it, was a challenge, and hurled at him, in hopes to catch him unprepared, the following abrupt sentence: "I doubt the possibility of the existence of a great cavern such as you have described. The superincumbent mass of earth would crush the strongest metal. No material known to man could withstand a pressure so great as would overlie an arch as large as that you depict; material would succumb even if the roof were made of steel." "Do not be so positive," he replied. "By what authority do you make this assertion?" "By the authority of common sense as opposed to an unreasonable hypothesis. You should know that there is a limit to the strength of all things, and that no substance is capable of making an arch of thousands of miles, which, according to your assertion, must have been the diameter of the roof of your inland sea."