A certain engineer set out to build a huge brick wall across Petersburg. He thinks over how to do this, does not sleep at night, and contemplates. Gradually, a circle of thinker-engineers is formed and a plan for building the wall is developed. It was decided to build the wall at night, so that everything should be built in one go to be a complete surprise. The workers are convening. There is a distribution. The city authorities are set aside, and finally the night comes when this wall should be built. Only four people know about the construction of the wall. The workers and engineers receive precise instructions on where to stand and what to do. Thanks to the exact calculation, the wall is built in one night. The next day, there is turmoil in Petersburg. And the inventor of
the wall himself is discouraged. On what to apply this wall, he himself did not know.