"The concept of legitimacy is analyzed in the article mainly within the bounds of academic discourse, the analysis being based on comprehending the specificity of the concept’s cognitive structures as the said specificity was revealing itself in the process of the concept’s cultural-historical evolution. Authority, as well as trust, are dealt with as the primary form of public legitimation. It is, furthermore, demonstrated that it was theological delimitation of ecclesiastical and temporal power in Christian Europe that became the initial ground for conceptualization of the legitimacy phenomenon. A number of observations on points of principle are made, related to the way the legitimacy concept was interpreted in the 17th to 19th centuries