This paper presents Bernard of Clairvaux as seen and interpreted by the Cistercian Abbot Isaac of Stella in his Sermon 52 In Assumptione Beatae Mariae. A comparison between the latter and Saint Bernard's sermon De tribus generibus emissionum (= De diversis 91) does not only reveal the important debt of Isaac to Bernard, but it also points to the innovative interpretation Isaac applies to Bernard's thought. Thus Isaac is shown to establish an original relation among ecclesiology, Mariology and a theology of individual religious experience.