In his autobiography The Oak and the Calf, Alexandr Solzhenitsyn recalls how he "wrote" in the concentration camps, where writing was forbidden, and how vulnerable his work was:

In the camp, this meant committing —many thousands of lines —to memory. To help me with this, I improvised decimal counting beads and, in transit to prisons, broke up matchsticks and used the fragments as tallies. As I approached the end of my sentence, I grew more confident of my powers of memory, and began writing down and memorizing prose—dialogue at first, but then, bit by bit, whole densely written passages…. But more and more of my time —in the end as much as one week every month— went into the regular repetition of all I had memorized.

Then came exile, and right at the beginning of my exile, cancer…. In December [1953] the doctors —comrades in exile— confirmed that I had at most three weeks left.

All that I had memorized in the camps ran the risk of extinction together with the head that held it. This was a dreadful moment in my life: to die on the threshold of freedom, to see all I had written, all that gave meaning to my life thus far, about to perish with me….

I hurriedly copied things out in tiny handwriting, rolled them, several pages at a time, into tight cylinders and squeezed these into a champagne bottle. I buried the bottle in my garden— and set off for Tashkent to meet the new year and to die. [In fact, he was treated and recovered completely.]