As a general rule the members of the blood royal of an Imperial or Royal house are addressed as "Imperial" or "Royal Highness" (_Altesse Imperiale_, _Royale_, _Kaiserliche_, _Konigliche Hoheit_) respectively. In Germany the reigning heads of the Grand Duchies bear the title of Royal or Grand Ducal Highness (_Konigliche_ or _Gross-Herzogliche Hoheit_), while the members of the family are addressed as _Hoheit_, Highness, simply. _Hoheit_ is borne by the reigning dukes and the princes and princesses of their families. The title "Serene Highness" has also an antiquity equal to that of "highness," for [Greek: galenotes] and [Greek: hemerotes] were titles borne by the Byzantine rulers, and serenitas and _serenissimus_ by the emperors Honorius and Arcadius. The doge of Venice was also styled _Serenissimus_. Selden (_op. cit._ pt. ii. ch. x. 739) calls this title "one of the greatest that can be given to any Prince that hath not the superior title of King." In modern times "Serene Highness" (_Altesse Serenissime_) is used as the equivalent of the German _Durchlaucht_, a stronger form of _Erlaucht_, illustrious, represented in the Latin honorific _superillustris_. Thackeray's burlesque title "Transparency" in the court at Pumpernickel very accurately gives the meaning. The title of _Durchlaucht_ was granted in 1375 by the emperor Charles IV. to the electoral princes (_Kurfursten_). In the 17th century it became the general title borne by the heads of the reigning princely states of the empire (_reichslandische Fursten_), as _Erlaucht_ by those of the countly houses (_reichstandische Grafen_). In 1825 the German Diet agreed to grant the title _Durchlaucht_ to the heads of the mediatized princely houses whether domiciled in Germany or Austria, and it is now customary to use it of the members of those houses. Further, all those who are elevated to the rank of prince (_Furst_) in the secondary meaning of that title (see PRINCE) are also styled _Durchlaucht_. In 1829 the title of _Erlaucht_, which had formerly been borne by the reigning counts of the empire, was similarly granted to the mediatized countly families (see _Almanack de Gotha_, 1909, 107).