Abstract
Some theories in science are like living organisms. They are born from each other, formed into each other, or continue their scientific lives together. It can be mentioned that there is such a relationship between the most famous works of the Soviet scientist Lev Gumilev (1912-1992), the theories of ethnogenesis and passionarnost. Although they are named with two different names, the connection between the aforementioned theories of the scientist should be examined in order to get to know Gumilev better and to understand his theories better. For this purpose, first of all, Gumilev’s life and scientific studies will be briefly mentioned in our study. Then, theory of ethnogenesis will be examined in detail. Afterward, the phases of ethnogenesis will be presented as a table and the theory of passionarnost will be introduced. The word passionarnost will first be examined semantically, and the meaning that the scientist wants to express will be revealed by using the word, which is a Gumilev’s specific term. Finally, the symbiotic relationship between the theories of ethnogenesis and passionarnost will be analyzed. To reveal the relationship between the theories of ethnogenesis and passionarnost will provide a holistic perspective on a number of historical events and a better analysis of the systematic connections between events.