(21) Then the LORD said to Moses, “Hold out your arm toward the sky that there may be darkness upon the land of Egypt, a darkness that can be touched.” (22) Moses held out his arm toward the sky and thick darkness descended upon all the land of Egypt for three days. (23) No man could see his brother, and for three days no one could get up from where he was; but all the Israelites enjoyed light in their dwellings.
Perhaps the Egyptians were depressed by the series of calamities that had struck them or by the realization of how much their own comfort depended on the enslavement of others. The person who cannot see his [sic] neighbour is incapable of spiritual growth, incapable of rising from where he [sic] is currently.
Harold Kushner in Etz Hayim, JPS Torah and Commentary, 2001
It was taught, Rabbi Meir says that the day begins when one can distinguish between a wolf and a dog.
Rabbi Akiva says between a donkey and a wild donkey. And other rabbis say: When one can see another person, from a distance of four cubits and recognize them.
In those early years, isolation became a habit. We were routinely charged for the smallest infractions and sentenced to isolation. The authorities believed that isolation was the cure for our defiance and rebelliousness. I found solitary confinement the most forbidding aspect of prison life. There was no end and no beginning; there is only one's own mind, which can begin to play tricks.
Nelson Mandela, The Long Walk to Freedom, 1994.
I had never been in solitary confinement. God’s companionship does not stop at the door of a jail cell. I don’t know whether the sun was shining at that moment. But I do know that once again I could see the light.
The Autobiography of Martin Luther King, Jr. Ed. Clayborne Carson, 2001, Chapter 18: Letter from a Birmingham Jail