ENThe article presents a discussion 1564/1566 between Stanislav Orihovski (Orzechowski, 1513-1566) and Augustyn Rotundus (Mieleski, c. 1520-1582), which has become an extraordinary phenomenon of political thought of the Polish Crown and the Grand Duchy of Lithuania. It is adequately represents the process of the union (Polish-Lithuanian Commonwealth), ended the Lublin union in 1569, and also outlines the intellectual horizons of the then elite and indicates the importance specific "ruthenian" experience for them to take appropriate decisions. Orihovsky defended the position of full incorporation the Grand Duchy of Lithuania in the Polish Crown. Rotundus criticized extremes of the Orihovski and defended the rights of the Grand Duchy of Lithuania. Article expands upon the author’s book (biography Orihovski), which was published in 2013.