The so-called imperial quaternions (German: Quaternionen der Reichsverfassung, lit. 'quaternions of the imperial constitution'; from Latin: quaterniō, lit. 'group of four soldiers')
were a conventional representation of the Imperial States of the Holy Roman Empire which first became current in the 15th century and was extremely popular during the 16th century.[3][4]
Apart from the highest tiers of the emperor, kings, prince-bishops and the prince electors, the estates are represented in groups of four. The number of quaternions was usually ten, in descending order of precedence:
The list could be shortened or expanded, by the mid-16th century to as many as 45.[5][6][7][8]
It is likely that this system was first introduced under Emperor Sigismund, who is assumed to have commissioned the frescoes in Frankfurt city hall in 1414.[9]
As has been noted from an early time, this representation of the "imperial constitution" does not in fact represent the actual constitution of the Holy Roman Empire, as some imperial cities appear as "villages" or even "peasants"[b] and the Burggrave of Stromburg[c] was an unknown entity even at the time. The representation of imperial subjects is also far from complete. The "imperial quaternions" are, rather, a more or less random selection intended to represent pars pro toto the structure of the imperial constitution.
Twelve vertical quaternions were shown under them, as follows — eight dukes being divided into two quaternions called "pillars" and "vicars", respectively:[10]
An Imperial Eagle beaker (German: Reichsadlerhumpen), or eagle glass, was a popular drinking vessel from the 16th until the late 18th century in the Holy Roman Empire. The enamelled glass was decorated with a double-headed eagle, usually in the shape of a Quaternion Eagle. The Reichsadler means "Imperial Eagle" or double-headed eagle which was the emblem of the empire, while "humpen" refers to a cylindrical drinking glass.[11][12] These beakers became the essential medium to represent the most popular explanatory model for the emergence of the Empire: the quaternion theory as represented by Hans Burgkmair.
The Imperial Eagle beakers showed the solidarity between the owner and the Empire and were very popular because of their decorativeness and luminous colors. But these drinking vessels were also valued for their generous size. Equally popular were the electors' beakers, which were decorated with illustrations of the emperor and electors as the most important representatives of the Empire.
Many good examples of Imperial Eagle beakers are on display in museums worldwide. At auctions well-preserved pieces achieve a selling price of up to several thousand euros.
Knorr von Rosenroth, Christian (1672). Anführung zur Teutschen Staats-Kunst [Introduction to the German State Art] (in German). Hofmann. Retrieved 4 November 2022 – via Google Books.
Legband, Hans (1905). "Zu den Quaternionen der Reichsverfassung" [On the Quaternions of the Imperial Constitution]. Archiv für Kulturgeschichte (in German). 3: 495–498.
Bund, Konrad (1987). Findbuch der Epitaphienbücher (1238)–1928 und der Wappenbücher (1190)–1801 [Inventory of the epitaph books (1238)–1928 and the heraldic books (1190)–1801] (in German). Kramer. ISBN3782903315.
Schubert, Ernst (1993). "Die Quaternionen" [The Quaternions]. Zeitschrift für historische Forschung (in German). 20: 1–63.