The paper deals with the personality traits of Gallo-Roman author Sidonius Apollinaris (~430–489) who was a representative of Late Roman nobility and clergyman as well. It wasn’t unusual situation for 4th-6th century’s Mediterranean world, when intellectual elite was a fueler for religious leaders. Nonetheless some of them underwent the crisis of identity, others continued to hold old values and way of life. Authors suggest the idea that Sidonius was a unique person who was able to rebuild his world perception, not breaking with the old attitudes associated with the aristocratic life, but at the same time accepting Christian morality with all his heart and becoming its proponent. It is possible if we consider him as a flexible thinking person on the base of achievements of psychology science. Sidonius was a flexible thinking person who react suitable on all changes without breaking, crisis of identity, because he saw the way how to adapt his old values and merits to new world. It means that antique and medieval culture aspects coexisted peacefully in his mind.