It dwells in my mind so!

I lie here on this great immovable bed—it is nailed down, I believe—and follow that pattern about by the hour. It is as good as gymnastics, I assure you. I start, we’ll say, at the bottom, down in the corner over there where it has not been touched, and I determine for the thousandth time that I will follow that pointless pattern to some sort of a conclusion.