In an attempt to take a new look at the figure of Élie Bertrand (1713–1797) as an outstanding representative of the Swiss enlightenment and learned mediator of this era, the author of this article focuses on his relations with Poland, covering the years 1761–1772. The groundwork for his considerations will be Élie Bertrand’s activities related to the education and upbringing of the Mniszech brothers: Michał Jerzy Wandalin (1742–1806) and Józef Jan Tadeusz (? ‒1797), his activity expressed in transposing enlightenment ideas into the Polish ground, in attempting to reform Poland and in informing European public opinion about Polish matters. By showing the multidirectional activity of Élie Bertrand in relation to Poland, the author of this article uses the following sources: a small extract from the Versailles correspondence obtained so far [Bibliothèque Municipale de Versailles] (Recueil des lettres écrites par messieurs les comtes de Mniszech et par Monsieur Bertrand à Madame la comtesse de Mniszech [1761–1768]); the little known correspondence of Élie Bertrand with the Mniszech family from 1761–1770, included in the collection of the Library of the National Institute of Ossoliński in Wrocław, correspondence stored in other European archival and library resources, known and completely unknown projects of Elie Bertrand, concerning the reform of Polish agriculture, the founding of the Academy of Sciences and Applied Arts in Warsaw, as well as a publishing house and bank situated in the Vistula capital, and articles dedicated to Poland by the Helvetic scholar, published in the Yverdon Encyclopedia. Showing Élie Bertrand’s involvement in the discussion about the socio-political situation in which Poland found itself in the first years of the reign of Stanisław August Poniatowski (1765–1766), and in the period preceding the Confederation of Bar (29 February 1768), the author of this article pays special attention to Élie Bertrand firm condemnation of religious intolerance and, at the same time, the deeply Calvinist favor of equal rights for dissidents. By presenting Élie Bertrand’s projects regarding the reform of the Commonwealth of Poland of that time, the author of the article highlights his physiocratic attitude and experience gained at the Berne Economic Society, which he wanted to transplant into the Polish ground. Discussing important and painful issues of anarchy and fanaticism for Poland’s internal situation at that time, the author of the article emphasizes, particularly, the legalistic position taken by Élie Bertrand concerning the above-mentioned issues, expressed in the proposed concept of freedom, understood as absolute submission to law, above all. It was also emphasized that Élie Bertrand’s involvement in Polish affairs was marked by deep sensitivity and concern, as evidenced by the preserved correspondence.