Rashi exerted a decisive influence on establishing the correct text of the Talmud. Up to and including his age, texts of each Talmudic tractate were copied by hand and circulated in yeshivas. Errors often crept in: sometimes a copyist would switch words around, and other times incorporate a student's marginal notes into the main text. Because of the large number of merchant-scholars who came from throughout the Jewish world to attend the great fairs in Troyes, Rashi was able to compare different manuscripts and readings in Tosefta, Jerusalem Talmud, Midrash, Targum, and the writings of the Geonim, and determine which readings should be preferred. However, in his humility, he deferred to scholars who disagreed with him. For example, in Chulin 4a, he comments about a phrase, "We do not read this. But as for those who do, this is the explanation..."