Researchers have focused for decades on the epistolographic legacy of individuals from various social groups. Letters are a valuable ‘complement’ for other sources, serving as an ‘insight’, giving the narrative a multi-voice, and, depending on the author’s social position, can provide many valuable details unfelt in other types of sources. Correspondence of public officials usually receives most attention from the researchers, because it reveals the mechanisms of the functioning of power. However, letters of the social elite also reveal different aspects of everyday life, including administration of domains, which have gained importance. The basis for this article became the letters by the elder of Merkinė, Antoni Kazimierz Sapieha (1689–1739), to Wojciech Kurzewski, administrator of this domain, kept in the Manuscript section of the Wroblewski Library of the Lithuanian Academy of Sciences. Due to his humble duties and difficult financial situation A. K. Sapieha cannot be considered one of the most prominent members of the Sapiehas family, although his persistent ambition to stay out of the “margins” of public life and, in particular, his involvement in 1733–1736 whirlwind of interregnum events, indicates that he was an extraordinary person. This is evidenced by his wide circle of correspondents, among whom we find not only close relatives but also a number of state officials and top hierarchs of the Church. Aspirations of the elder of Merkinė to participate in the political life of the state have already been noticed by the researchers, however his daily economic activities have not been researched at all. Analysis of the letters from the 1720–1732 period by the elder of Merkinė Antoni Kazimierz Sapieha to Wojciech Kurzewski, administrator of this domain, reveal a significant part of A. K. Sapieha’s daily life, i.e. the nature of administration of the domain, which required considerable effort, attention and time from the elder of Merkinė. The article deals with the subject matter of letters, economic activities carried out in the eldership of Merkinė, and requirements for the administrator. All of this provides an opportunity not only to reconstruct the relationship between Sapieha and Kurzewski, but also to see the broader issues that each major landowner has faced (or may have faced).