I believe that very few men are capable of estimating the immense amount of torture and agony which this dreadful punishment, prolonged for years, inflicts upon the sufferers. . . . I hold this slow and daily tampering with the mysteries of the brain, to be immeasurably worse than any torture of the body: and because its ghastly signs and tokens are not so palpable to the eye and sense of touch as scars upon the flesh; because its wounds are not upon the surface, and it extorts few cries that human ears can hear; therefore I the more denounce it, as a secret punishment which slumbering humanity is not roused up to stay.-- Adam Gopnik quotes from Charles Dickens on solitary confinement in an outstanding piece on incarceration in the United States. Six million people are under correctional supervision in the U.S.—more than were in Stalin’s gulags. At any one time around 50,000 of them are in solitary confinement.