[I]n my specially isolated cell I was, to a very considerable extent, undisturbed, especially in the first five months after the sentence when I was in the dark and therefore necessarily inactive physically. In the dark there is little one can do except thjink, and the absence of anything to divert one’s thoughts gives them an intensity seldom experienced in normal conditions.

Edith Bone, Seven Years Solitary, London, 1957, p. 103