Bede : Festus said in a loud voice: You are insane, Paul. He deemed it insanity that a man in chains, instead of just defending himself from external accusations, made a speech about the conscience by which he gloried inside and reviewed all the miracles of the revelation by which he was transformed from a persecutor into an apostle, and discussed the dispensation of our Redeemer and argued vehemently about the resurrection of the dead. Indeed, just as there is the foolish madness of the prodigal son feeding pigs after abandoning his father, so there is spiritual madness, that is, true madness, about which the Apostle says: "For whether we are out of our mind, it is for God; or whether we be sober, it is for you." And in comparison to this, the Psalmist sings: "Blessed is the man who has the name of the Lord as his hope, and has not looked to vanities and false insanities" (Psalms 39). — Commentary on Acts John Chrysostom : Festus saw the boldness, and what says he? For Paul was all along addressing himself to the king-he was in a manner annoyed, and says to him, "Thou art beside thyself, Paul:" for, "while he thus discoursed, Festus said with a loud voice, Paul, thou art beside thyself: much learning doth make thee mad." What then says Paul? With gentleness, "I am not mad," says he, "most noble Festus; but speak forth the words of truth and soberness." — Homily on Acts 52 Oecumenius : Since he was always conversing with the king, as if Festus had suffered something, and seeing the boldness, from anger and outrage, he says, "You are mad." — Commentary on Acts