This paper provides an overview of the early considerations regarding the phenomenon of plagiarism – from Greco-Roman antiquity to the time when a thorough study examining literary theft in its textual, legal, and moral manifestations was printed, i. e. “Philosophical Dissertation on Literary Plagiarism” by Jacob Thomasius. Although the issue of plagiarism was very vital in ancient times, all the oldest considerations concerning the appropriation of other people’s texts were essentially pragmatic moves or reactions rather than purposeful theoretical interpretations of (...) the subject. However, in addition to the situational grounds of the accusation, they can reveal certain principles that, according to estimations of the time, could prevent or refute allegations of plagiarism. It was enough if the author stated, albeit generally but clearly, that the fragments of other people’s texts, whether altered or not, were used. It was also acceptable if the reader believed that the author considered his borrowings recognizable to educated readers. Another reason for the elimination of possible accusations was the factor of competition – the author’s desire to adapt the achievements of another cultural environment in his own one, significantly improving them. The medieval and early modern materials generally testify to the relevance of ancient views and reveal some new problems. This is, in particular, the incompatibility of new more formalized ideas about authorship and traditional educational practices, which encouraged the uncontrolled use of others’ texts. Some authors also emphasized that plagiarism was an obstacle to the development of science. The paper ends with examples that show how European ideas about the rules of using others’ writings may help interpret the writing methods of the early modern Ukrainian authors, including philosophers. (shrink)