All day I turned these facts over in my mind, endeavouring to hit upon some theory which could reconcile them all, and to find that line of least resistance which my poor friend had declared to be the starting-point of every investigation. I confess that I made little progress. In the evening I strolled across the Park, and found myself about six o’clock at the Oxford Street end of Park Lane. A group of loafers upon the pavements, all staring up at a particular window, directed me to the house which I had come to see. A tall, thin man with coloured glasses, whom I strongly suspected of being a plainclothes detective, was pointing out some theory of his own, while the others crowded round to listen to what he said. I got as near him as I could, but his observations seemed to me to be absurd, so I withdrew again in some disgust. As I did so I struck against an elderly, deformed man, who had been behind me, and I knocked down several books which he was carrying. I remember that as I picked them up, I observed the title of one of them, The Origin of Tree Worship