It was one small word which finally rent these two bodies of Christendom forever apart.  It was only the word filioque which made the impassable gulf dividing them.  The Latins maintained that the Holy Spirit proceeded from the Father—­and the son; the Greeks that it descended from the Father alone.  It was the undying controversy concerning the relations and the attributes of the three Members of the Trinity; and the insoluble question was destined to break up Greek and Catholic Church alike into numberless sects and shades of belief or unbelief; and over this Christological controversy, rivers of blood were to flow in both branches of Christendom.

The theological question involved was of course too subtle for ordinary comprehension.  But although men on both sides stood ready to die for the decisions of their councils which they did not understand, there was underlying the whole question the political jealousy existing between the two:  Byzantium, embittered by the effacement of its political jurisdiction in the West, exasperated at the overweening pretensions of Roman bishops; Rome, watching for opportunity to cajole or compel the Eastern Church to submit to her authority and headship.

Such was the condition of things when Russia allied herself in that most vital way with the empire in the East.  It is impossible to measure the importance of the step, or to imagine what would have been the history of that country had Vladimir decided to accept the religion of Rome and become Catholic, as the Slav in Poland had already done.  By his choice not only is it possible that he added some centuries to the life of the Greek Empire itself, but he determined the type of Russian civilization.  When she allied herself with Byzantium instead of Rome, Russia separated herself from those European currents from which she was already by natural and inherited conditions isolated.  She thus prolonged and emphasized the Orientalism which so largely shaped her destiny, and produced a nationality absolutely unique in the family of European nations, in that there is but one single root in Russia which can be traced back to the Roman Empire; and whereas most of the European civilizations are built upon a Roman foundation, there is only one current in the life of that nation to-day which has flowed from a Latin source:  that is a judicial code which was founded (in part) upon Roman law as embodied by Justinian, Emperor of the Empire in the East (527-565).

CHAPTER V

PRINCIPALITIES—­EXPANSION NORTHWARD