Sidney Rittenberg Sr. is co-author, with Amanda Bennett, of “The Man Who Stayed Behind.” He was jailed twice by Mao Zedong, from 1949 to 1955 and from 1968 to 1977, on charges of being an American spy.

Feb. 22, 1968. As they walked me down the gray prison corridor toward my cell, I was startled to see the same medieval torture scene I had endured 19 years earlier. Eleven solitary cells still there in a row; 11 wooden slabs, with iron hasps and double padlocks.

They look like iceboxes, I thought, and there’s a human being entombed in every one of them.

Door No. 11 opened and clanged shut behind me. The bare cell held a “bed” (a wooden door laid across two shortened saw-horses), a cold-water sink, a commode with no seat. That was it. There was a steel grate over the barred half-window overhead and another around the two light bulbs, a brighter one for daytime and a dimmer one for night. The cell was about six paces long and three paces wide — little room for exercise. A peephole in the door and another by the commode afforded the guards a clear view.

Solitude without privacy.

Near the bottom of the door was a foot-long slot, opened at meal time so I could stick out my bowl for the food cart. Around the peephole was another little slot, opened when guards needed to bark orders at me.

There was a thin quilt on the bed and a thinner mat on which to lie.

For the first four-plus years of my second incarceration, prisoners were not permitted to lie down outside of regulation sleeping hours. We were not permitted to voice any sound.

Later, we were permitted to turn over in bed at night — before that, one had to sleep facing the guard, with hands between neck and navel.

I was supposed to have 30 minutes a day in a roofless cell from which one could see the sky and perhaps even get a bit of sunshine. This was honored mainly in the breach.

I lived like that in a Chinese prison outside Beijing for 10 years. Earlier, I had been locked in solitary for six years, in an old warlord prison with no plumbing and no steam heat — the first year in a cell that was kept in total darkness.

U.S. scientists have pointed out that solitary confinement is a form of torture and that few can retain their sanity after a long period in isolation. It is routinely used in China to force confessions out of suspects. I know many who have been through this, and I have seen that the survivors are often partially or wholly mentally crippled.

Imagine how shocked I was to find years later that we, the United States of America, hold more human beings in long-term solitary confinement than any other country in the world. I had supposed it would be China — but, no, it’s us.

The commonwealth of Virginia is one of the worst offenders.

During my first year in solitary darkness, after being forced to take some sort of drugs, my mind collapsed into a state of indescribable anguish and hysteria. I lived in this extreme depression and loss of all control for months, until my captors relieved the pressure, changed my living conditions and gave me some new drugs, which they said were to relieve the effects of the earlier drugs. They also, for a few months, provided me with the companionship of friendly guards outside the cell.

I gradually regained my sanity, but I was left with strong post-traumatic panic syndrome for the next 20-odd years. I would suddenly start palpitating, break out in a cold sweat and feel a terrible pressure on my forehead as though it was being squeezed in an iron hoop. These attacks would last for less than one minute, but each time I was terrified that the horribly painful madness I had been through would return.

Finally, during my later 10 years in solitary, I learned how to eliminate these terrifying episodes by using techniques that I later learned are called cognitive therapy.

How I learned to survive and to regain my health is not the point. The point is that solitary confinement is undeniably cruel and unusual punishment. Long-term solitary confinement should be declared unconstitutional. And it is a disgrace for the great commonwealth of Virginia, given the glorious role it has played in our country’s history and its proximity to our nation’s capital, to be guilty of large-scale imposition of this torture on any human being.