EMINENCE (Lat. eminentia), a title of honour now confined to the cardinals of the Church of Rome. It was originally given as a complimentary title to emperors, kings, and then to less conspicuous persons. The Roman empire of the 4th century adopted from the "vanity of the East the forms and ceremonies of ostentatious greatness." Gibbon includes in the "profusion of epithets" by which "the purity of the Latin language was debased," and which were lavished on "the principal officers of the empire," "your Sincerity, your Gravity, your Excellency, your Eminence, your sublime and wonderful Magnitude, your illustrious and magnificent Highness." From the notitia dignitatum it passed into the Latin of the middle ages as a flattering epithet, and was applied in the church and by the popes to the dignified clergy at large, and sometimes as a pure form of civility to churchmen of modest rank. On the 10th of June 1630, Urban VIII. confined the use of the titles Eminentiae and Eminentissimi to the cardinals, to imperial electors, and to the master of the Hospital of St John of Jerusalem (order of the Knights of Malta). Since the dissolution of the Holy Roman Empire, and the entire change, if not actual destruction, of the order of St John, the title "eminence" has become strictly confined to the cardinals. Before 1630 the members of the Sacred College were "Illustrissimi" and "Reverendissimi." It is, therefore, not correct to speak of a cardinal who lived before that time as "his Eminence."
See du Cange, Glossarium mediae et infimae latinitatis (Niort and London, 1884), s.v. "Eminentia."
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)