Evaluating history as a mentor of life, the author sees the purpose of his research as to show the change in the foundations and conditions of the social and political development of Poland in the past, to find out the reasons for this development and the subsequent decline, to characterize the people and outstanding personalities in each era and departments into which each era falls apart. Particular attention is paid to the XV and XVI centuries - the time of prosperity of Poland. The author urges the reader to respect the past, but not to "turn it into a mummy, but to use history lessons wisely and soberly."