Summary. — This study first lists the principal interpretations so far of the phrase: 6V Evxr\c, Xoyou tou -reap' auTou, in chapter 66 of St. Justin's First Apology. Then, following some comments of a methodological nature and by means of detailed textual analysis, the conclusion is arrived at that St. Justin sees in the Eucharistic celebration, inseparably united to the prayer — tvxh — spoken by the one who presides — -reposo'TW? —, an operative presence of the Divine « Logos » who accomplished the work of the Incarnation.