Of no human institution is this more true than of the great medieval church of Gregory and Innocent when viewed in the light of its claims to unlimited temporal and spiritual sovereignty.  In striking down the headship of the emperors, it would have reduced Europe to a sort of Oriental caliphate, had it not been checked by the rising spirit of nationality already referred to.  But there was another and even mightier agency coming in to curb its undue pretensions to absolute sovereignty.  That same thirteenth century which witnessed the culmination of its power witnessed also the first bold and determined manifestation of the Protestant temper of revolt against spiritual despotism.  It was long before this that the earliest Protestant heresy had percolated into Europe, having its source, like so many other heresies, in that eastern world where the stimulating thought of the Greeks busied itself with the ancient theologies of Asia.  From Armenia in the eighth century came the Manichaean sect of Paulicians into Thrace, and for twenty generations played a considerable part in the history of the Eastern Empire.  In the Bulgarian tongue they were known as Bogomilians, or men constant in prayer.  In Greek they were called Cathari, or “Puritans.”  They accepted the New Testament, but set little store by the Old; they laughed at transubstantiation, denied any mystical efficiency to baptism, frowned upon image-worship as no better than idolatry, despised the intercession of saints, and condemned the worship of the Virgin Mary.  As for the symbol of the cross, they scornfully asked, “If any man slew the son of a king with a bit of wood, how could this piece of wood be dear to the king?” Their ecclesiastical government was in the main presbyterian, and in politics they showed a decided leaning toward democracy.  They wore long faces, looked askance at frivolous amusements, and were terribly in earnest.  Of the more obscure pages of mediaeval history, none are fuller of interest than those in which we decipher the westward progress of these sturdy heretics through the Balkan peninsula into Italy, and thence into southern France, where toward the end of the twelfth century we find their ideas coming to full blossom in the great Albigensian heresy.  It was no light affair to assault the church in the days of Innocent iii.  The terrible crusade against the Albigenses, beginning in 1207, was the joint work of the most powerful of popes and one of the most powerful of French kings.  On the part of Innocent it was the stamping out of a revolt that threatened the very existence of the Catholic hierarchy; on the part of Philip Augustus it was the suppression of those too independent vassals the Counts of Toulouse, and the decisive subjection of the southern provinces to the government at Paris.  Nowhere in European history do we read a more frightful story than that which tells of the blazing fires which consumed thousand after thousand of the most intelligent