In 326 Constantine went to Rome to celebrate the completion of his twentieth year of reign. Diocletian had done the same—the only occasion upon which that great Emperor had ever set foot in the ancient capital, and even then he made all possible haste to quit it. But whereas Diocletian had travelled thither with the intention of abdicating immediately afterwards, Constantine had no such act of self-abnegation in his mind. Yet he was in no festival mood. Not long after his arrival, there took place the ancient ceremony known as the Procession of the Knights, who rode to the Capitol to pay their vows to Jupiter—the religious ceremony which attended the annual revision of the equestrian lists. Constantine contemptuously stayed within his palace on the day and disdained to watch the Knights ride by. His absence was made the pretext for some street rioting, which, we can hardly doubt, had been carefully engineered beforehand. Rome, still overwhelmingly pagan in its sympathies, had doubtless heard with bitter anger how the Emperor, the head of the old national religion, had been taking part in a General Council of the Christian Church, had admitted bishops and confessors to the intimacy of his table, and had boldly declared himself the champion of Christianity. Constantine’s pointed refusal to countenance a time-honoured ceremony which, while itself of no extraordinary importance, might yet be taken as typical of the ancient order of things, would easily serve as pretext for a hostile demonstration. Demonstrations in Rome no longer menaced the throne now that the barracks of the Prætorians were empty, but the incident would serve to confirm the suspicions already clouding the mind of the Emperor. We can read those suspicions most plainly in an edict which he had issued at Nicomedia a few months before. It was addressed to his subjects in every province (_Ad Universos Provinciales_), and in it the Emperor invited all and sundry to come forward boldly and keep him well informed of any secret plotting of which they happened to be cognisant. No matter how lofty the station of the conspirator might be, whether governor of a province, officer of the army, or even friend and associate of the Emperor, if any one discovered anything he was to tell what he knew, and the Emperor would not be lacking either in gratitude or substantial reward. “Let him come without fear,” ran the edict, “and let him address himself to me! I will listen to all: I will myself conduct the investigation[109]: and if the accuser does but prove his charge, I will vindicate my wrongs. Only let him speak boldly and be sure of his case!” ----- Footnote 109: _Intrepidus et securus accedat: interpellet me. Ipse audiam omnia, ipse cognoscam._ -----