Instead an Epigraph There is a parable that the population of one small south russian town in the old days was divided between parishioners of the Christian church and the Jewish synagogue. A Christian priest was already heavily wiser by a life experience, and the rabbi was still quite young and energetic. One day the rabbi came to the priest for advice. - My colleague, - he said, - I lost my bike. I feel that it was stolen by someone from there, but who did it I can not identify. Tell me what to do. - Yes, I know one scientific method for this case, - replied the priest. You should do this: invite all your parishioners the synagogue and read them the ≪Ten Commandments of Moses≫. When you read ≪Thou shalt not steal≫, lift your head and look carefully into the eyes of your listeners. The listener who turns his eyes aside will be the guilty party. A few days later, the rabbi comes to visit the priest with a bottle of Easter-vodka and on his bike. The priest asked the rabbi to tell him what happened in details. The rabbi told the priest that his theory had worked in practice and the bike was found. The rabbi relayed the story: - I collected my parishioners and began to preach. While I approached reading the ≪Do not commit adultery≫ commandment I remembered then where I forgotten my bike! So it is true: there is indeed nothing more practical than a good theory!