Its oddity began with its very first page. Ordinarily on the first page of a diary you look for the owner's name and address. Here was no address; on the other hand there was a string of names. There were, to be exact, eight of them, with space for more, the whole written in his small fine hand and disposed in a neat vertical column. This block of names might have been from the everyday-book of any working novelist, part of whose task it is to label his puppets appropriately. I had no reason to suppose that hitherto Derwent Rose had ever gone under any name but his own. It had certainly occurred to me that he might sooner or later have to do so. This appeared to be a preparation for such a contingency. His own name of Derwent Rose, by the way, did not appear. Opposite the names a diagram had been pasted into the book. It was on squared paper, such as draughtsmen use, of so many squares to the inch; and these squares had been numbered horizontally along the top with the years from 1891 to 1920, that is to say from his own age of sixteen on. Lower down the page, and still horizontally, red and black lines of various lengths were set in echelon. These were sprinkled over with numbers, which I discovered to refer to the pages that followed. Certain arrows pointed in opposite directions. Over these were written, in one direction, the words "'A' memory," in the other the words "'B' memory." This completed the horizontal arrangement. The vertical set-out appeared to have given him much more trouble. It did not appear to have been completed. A heavy black line ruled up through the year 1905 was lettered "true middle," but that appeared to be the only stable term of its kind. The rest was a mere rain of pencil-lines, momentary false middles that apparently he had tried to seize in passing. I knew by this time how unseizable they were. Not one of them lay on the right side of the true middle line. All overstepped it and travelled in a gradual procession towards the left of the diagram. On other pages I found other diagrams. These were merely enlarged details of the foregoing, with days of the month instead of years. One wild chart was an attempt to combine the whole in a single comprehensive statement. But this had completely beaten him. A serpentine whip-lash of pencil had been flung so viciously across it that one almost heard the crack. The rest of the book consisted of text. I was of course prepared at any moment to receive a telegram or letter asking for the book's instant return. If it really contained the key to his speed of retrogression it was probably the most important thing he had in the world. Therefore, lest he should claim it before I had finished with it, it stayed in my breast pocket when it was not actually in my hand.