A theory is an ensemble of concepts which explains a part of reality. Theories are not necessary but they are very useful. Mankind has lived for thousands of years without knowing physics but it is useful to know physics, you can drive cars and have electricity and computers and telephones. Medicine men have cured or killed humans for thousands of years but it is useful to have hospitals and laboratories and drugs and all that the medical science has created, you can live longer and better. People have translated for thousands of years, nowadays half the planet is busy translating what the other half says. The XXth century is being called many names, the best name is the "century of translation". Never before in the course of huma...