i trust that i am not more dense than my neighbours, but i was always oppressed with a sense of my own stupidity in my dealings with sherlock holmes. here i had heard what he had heard, i had seen what he had seen, and yet from his words it was evident that he saw clearly not only what had happened but what was about to happen, while to me the whole business was still confused and grotesque. as i drove home to my house in kensington i thought over it all, from the extraordinary story of the red-headed copier of the encyclopædia down to the visit to saxe-coburg square, and the ominous words with which he had parted from me. what was this nocturnal expedition, and why should i go armed?