This article deals with the question of possible reasons for Conrad Gessner quoting an aphorism from Julian the Apostate’s letter (Ep. 23, to Ecdicius, prefect of Egypt) under the name of Marcus Aurelius in the preface to his Bibliotheca universalis, the first European universal bibliography (1545). Basing on the articles in Bibliotheca devoted to the above-mentioned authors, we can conclude that Gessner was directly acquainted with Julian’s letters (he obviously relied on the collection of Greek letters published by Aldus Manutius in 1499 under the title Epistolae diversorum philosophorum, oratorum, rhetorum), whereas no texts of Marcus (including fragmentary ones) were available to him by 1545. The topic of the search for a library and the question of how to treat the books written by religious opponents, which occupy a central place in Julian’s letter to Ecdicius, must have attracted Gessner’s attention, especially since the solution proposed by Julian turned out to be consonant with Gessner’s thoughts expressed in Bibliotheca. Thus, the false attribution of the quotation, undoubtedly deliberate, was, on the one hand, to prevent possible reproaches from conservative readers for quoting an anti-Christian author, and, on the other hand, to draw attention of a competent reader to Julian’s text