By convention epinician poetry claims to be both obligatory and truthful, yet in the intersection of obligation and truth lies a seeming paradox: the poet presents his poetry as commissioned by a patron but also claims to be unbiased enough to convey the truth. In Slater's interpretation Pindar reconciles this paradox by casting his relationship to the patron as one of guest-friendship: when he declares himself a guest-friend of the victor, he agrees to the obligation ‘a) not to be envious of his xenos and b) to speak well of him. The argumentation is: Xenia excludes envy, I am a xenos, therefore I am not envious and consequently praise honestly’. Slater observes that envy may foster bias against the patron, but the problem of pro-patron bias remains: does the poet's friendship with and obligation to his patron produce praise at the expense of truth?