After the introduction to the conference presented over the past two weeks revolving around the elder Theona's conversion and his choice of pursuing the absolute good of following Christ and pursuing purity of heart, the dialogue itself begins.  The two friends asks Theonas about the custom of not kneeling during the 50 days of Pentecost and of observing a modified schedule of fasting during that season.  Theonas first makes a bow to the authority of the ancients.  Then, addressing himself to the issue of fasting, he distinguishes between absolute goods and absolute evils on the one hand and those things that are, on the other hand, either good or bad depending on how they are used.  Fasting is not an absolute good; if it were, then it would be wrong ever to eat.  It is, instead, something indifferent, which is practiced for the sake of acquiring an absolute and essential good.  The characteristics of an absolute good, however, are that "it is good by itself and not by reason of something else . . .necessary for its own sake and not for the sake of something else . . . unchangeable and always good . . . its removal and cessation cannot but bring on the gravest evil and that similarly, the essential evil, which is its opposite, cannot ever become good." This definition, so typical of Cassian in its precision, can in no way apply to fasting.  With two allusions to the subordination of fasting to the acquisition of purity of heart we are once again drawn back to the atmosphere of the first conference.