When I was ten years old I got my first aquarium. It was not big. Its capacity was about 5 gallons. I foresaw this tank of glass as a beautiful underworld full of exotic fish and tropical plants. Being very enthusiastic about making my own world I bought different fish species. In a month the number of fish in the tank exceeded twenty. But there was no beautiful world as I expected. Fish could not grow and got sick. Bigger fish tried to kill weaker ones. All fish made a lot of crap as well as snails that were supposed to clean everything. I did not know what to do. My idea of the beautiful world was destroyed. In two months I lost almost all population. At that time I bought a bigger tank. There were about five fishes left and I put all of them in the new tank. Surprisingly, they become to grow fast and got healthier. As I learned later a fish needs a certain amount of water to own in order to live, grow, and reproduce the breed. This amount of water cannot be shared with the others. Nowadays I am aware that humans live by the same rule. If the number of people confined in the closed space reaches its critical limit, the Christian concept of the peaceful brotherhood collapses and the natural selection pattern of behavior derived from the human unconsciousness dominates with all unpredictable brutality and animal inhumanity.