Before we proceed to draw another negative conclusion from the principle of the one community, we must enter a brief caveat in regard to the conclusion which has just been drawn.  We cannot altogether take away the State from the Middle Ages by a stroke of the pen and the sweep of a paradox.  There were states in mediaeval Europe, and there were kings who claimed and exercised imperium.  These things caused the theorists, and particularly the Roman lawyers, no little trouble.  It was difficult to reconcile the unity of the imperium with the multiplicity of kings.  Some had recourse to the theory of delegation, and this seems to be the theory of the De Monarchia of Dante.  But there was one contemporary of Dante who said a wise thing, prophetic of the future. Rex est in regno suo, wrote Bartolus of Sassoferrato, imperator regni sui.  In that sentence we may hear the cracking of the Middle Ages.  When kings become ‘entire emperors of their realms’ (the phrase was used in England by Richard II, and the imperial style was affected by Henry VIII), unity soon prepares to fly out of the window.  But she never entirely took flight until the Reformation shattered the fabric of the Church, and made kings into popes as well as emperors in their dominions.

We may now turn to draw another conclusion from the mediaeval principle of unity.  To-day the world recognizes, and has recognized for nearly four centuries, not only a distinction between States, but also a distinction between two societies in each State—­the secular and the religious.  These two societies may have different laws (for instance, in the matter of marriage), and conflicts of duties and of jurisdictions may easily arise in consequence.  The State may permit what the Church forbids; and in that case the citizen who is also a churchman must necessarily revolt against one or other of the societies to which he belongs.  The conflict between the two societies and the different obligations which they impose was a conflict unknown to the Middle Ages.  Kings might indeed be excommunicated, and in that event their subjects would be compelled to decide whether they should disobey excommunicated king or excommunicating pope.  But that was only a conflict between two different allegiances to two different authorities; it was not a conflict between two different memberships of two different societies.  The conflict between the two societies—­Church and State—­was one which could hardly arise in the Middle Ages, because there was only a single society, an undivided Christian commonwealth, which was at one and the same time both Church and State.  Because there was only one society, baptism counted as admission both to churchmanship and to citizenship, which were one thing, and one only, in the Christian commonwealth; and for the same reason excommunication, which shut the offender from all religious life, excluded him equally and by the same act from every civil right.  The excommunicated