To that position three cardinal duties were attached. He who held it must typify spiritual unity, must preserve peace, must be a fountain of that by which alone among imperfect men peace is preserved and restored, law and justice. The first of these three objects was sought not only on religious grounds, but also from that longing for a wider brotherhood of humanity towards which, ever since the barrier between Jew and Gentile, Greek and barbarian, was broken down, the aspirations of the higher minds of the world have been constantly directed. Placed in the midst of Europe, the Emperor was to bind its tribes into one body, reminding them of their common faith, their common blood, their common interest in each other’s welfare. And he was therefore above all things, professing indeed to be upon earth the representative of the Prince of Peace, bound to listen to complaints, and to redress the injuries inflicted by sovereigns or people upon each other; to punish offenders against the public order of Christendom; to maintain through the world, looking down as from a serene height upon the schemes and quarrels of meaner potentates, that supreme good without which neither arts nor letters, nor the gentler virtues of life, can rise and flourish. The mediæval Empire was in its essence what the modern despotisms that mimic it profess themselves: the Empire was peace: the oldest and noblest title of its head was ‘Imperator pacificus’.
-James Viscount Bryce, The Holy Roman Empire