DIET, a term used in two senses, (1) food or the regulation of feeding (see Dietary and Dietetics), (2) an assembly or council (Fr. diète; It. dieta; Low Lat. diaeta; Ger. Tag). We are here concerned only with this second sense. In modern usage, though in Scotland the term is still sometimes applied to any assembly or session, it is practically confined to the sense of an assembly of estates or of national or federal representatives. The origin of the word in this connotation is somewhat complicated. It is undoubtedly ultimately derived from the Greek (Lat. diaeta), which meant "mode of life" and thence "prescribed mode of life," the English "diet" or "regimen." This was connected with the verb , in the sense of "to rule," "to regulate"; compare the office of at Athens, and dieteta, "umpire," in Late Latin. In both Greek and Latin, too, the word meant "a room," from which the transition to "a place of assembly" and so to "an assembly" would be easy. In the latter sense the word, however, actually occurs only in Low Latin, Du Cange (Glossarium, s.v.) deriving it from the late sense of "meal" or "feast," the Germans being accustomed to combine their political assemblies with feasting. It is clear, too, that the word diaeta early became confused with Lat. dies, "day" (Ger. Tag), "especially a set day, a day appointed for public business; whence, by extension, meeting for business, an assembly" (Skeat). Instances of this confusion are given by Du Cange, e.g. diaeta for dieta, "a day's journey" (also an obsolete sense of "diet" in English), and dieta for "the ordinary course of the church," i.e. "the daily office," which suggests the original sense of diaeta as "a prescribed mode of life."
The word "diet" is now used in English for the Reichstag, "imperial diet" of the old Holy Roman Empire; for the Bundestag, "federal diet," of the former Germanic confederation; sometimes for the Reichstag of the modern German empire; for the Landtage, "territorial diets" of the constituent states of the German and Austrian empires; as well as for the former or existing federal or national assemblies of Switzerland, Hungary, Poland, etc. Although, however, the word is still sometimes used of all the above, the tendency is to confine it, so far as contemporary assemblies are concerned, to those of subordinate importance. Thus "parliament" is often used of the German Reichstag or of the Russian Landtag, while the Landtag, e.g. of Styria, would always be rendered "diet." In what follows we confine ourselves to the diet of the Holy Roman Empire and its relation to its successors in modern Germany.
The origin of the diet, or deliberative assembly, of the Holy Roman Empire must be sought in the placitum of the Frankish empire. This represented the tribal assembly of the Franks, meeting (originally in March, but after 755 in May, whence it is called the Campus Maii) partly for a military review on the eve of the summer campaign, partly for deliberation on important matters of politics and justice. By the side of this larger assembly, however, which contained in theory, if not in practice, the whole body of Franks available for war, there had developed, even before Carolingian times, a smaller body composed of the magnates of the Empire, both lay and ecclesiastical. The germ of this smaller body is to be found in the episcopal synods, which, afforced by the attendance of lay magnates, came to be used by the king for the settlement of national affairs. Under the Carolingians it was usual to combine the assembly of magnates with the generalis conventus of the "field of May," and it was in this inner assembly, rather than in the general body (whose approval was merely formal, and confined to matters momentous enough to be referred to a general vote), that the centre of power really lay. It is from the assembly of magnates that the diet of medieval Germany springs. The general assembly became meaningless and unnecessary, as the feudal array gradually superseded the old levy en masse, in which each freeman had been liable to service; and after the close of the 10th century it no longer existed.
The imperial diet (Reichstag) of the middle ages might sometimes contain representatives of Italy, the regnum Italicum; but it was practically always confined to the magnates of Germany, the regnum Teutonicum. Upon occasion a summons to the diet might be sent even to the knights, but the regular members were the princes (Fürsten), both lay and ecclesiastical. In the 13th century the seven electors began to disengage themselves from the prince as a separate element, and the Golden Bull (1356) made their separation complete; from the 14th century onwards the nobles (both counts and other lords) are regarded as regular members; while after 1250 the imperial and episcopal towns often appear through their representatives. By the 14th century, therefore, the originally homogeneous diet of princes is already, at any rate practically if not yet in legal form, divided into three colleges - the electors, the princes and nobles, and the representatives of the towns (though, as we shall see, the latter can hardly be reckoned as regular members until the century of the Reformation). Under the Hohenstaufen it is still the rule that every member of the diet must attend personally, or lose his vote; at a later date the principle of representation by proxy, which eventually made the diet into a mere congress of envoys, was introduced. By the end of the 13th century the vote of the majority had come to be regarded as decisive; but in accordance with the strong sense of social distinctions which marks German history, the quality as well as the quantity of votes was weighed, and if the most powerful of the princes were agreed, the opinion of the lesser magnates was not consulted. The powers of the medieval diet extended to matters like legislation, the decision upon expeditions (especially the expeditio Romana), taxation and changes in the constitution of the principalities or the Empire. The election of the king, which was originally regarded as one of the powers of the diet, had passed to the electors by the middle of the 13th century.
A new era in the history of the diet begins with the Reformation. The division of the diet into three colleges becomes definite and precise; the right of the electors, for instance, to constitute a separate college is explicitly recognized as a matter of established custom in 1544. The representatives of the towns now become regular members. In the 15th century they had only attended when special business, such as imperial reform or taxation, fell under discussion; in 1500, however, they were recognized as a separate and regular estate, though it was not until 1648 that they were recognized as equal to the other estates of the diet. The estate of the towns, or college of municipal representatives, was divided into two benches, the Rhenish and the Swabian. The estate of the princes and counts, which stood midway between the electors and the towns, also attained, in the years that followed the Reformation, its final organization. The vote of the great princes ceased to be personal, and began to be territorial. This had two results. The division of a single territory among the different sons of a family no longer, as of old, multiplied the voting power of the family; while in the opposite case, the union of various territories in the hands of a single person no longer meant the extinction of several votes, since the new owner was now allowed to give a vote for each of his territories. The position of the counts and other lords, who joined with the princes in forming the middle estate, was finally fixed by the middle of the 17th century. While each of the princes enjoyed an individual vote, the counts and other lords were arranged in groups, each of which voted as a whole, though the whole of its vote (Kuriatstimme) only counted as equal to the vote of a single prince (Virilstimme). There were six of these groups; but as the votes of the whole college of princes and counts (at any rate in the 18th century) numbered 100, they could exercise but little weight.
The last era in the history of the diet may be said to open with the treaty of Westphalia (1648). The treaty acknowledged that Germany was no longer a unitary state, but a loose confederation of sovereign princes; and the diet accordingly ceased to bear the character of a national assembly, and became a mere congress of envoys. The "last diet" which issued a regular recess (Reichsabschied - the term applied to the acta of the diet, as formally compiled and enunciated at its dissolution) was that of Regensburg in 1654. The next diet, which met at Regensburg in 1663, never issued a recess, and was never dissolved; it continued in permanent session, as it were, till the dissolution of the Empire in 1806. This result was achieved by the process of turning the diet from an assembly of principals into a congress of envoys. The emperor was represented by two commissarii; the electors, princes and towns were similarly represented by their accredited agents. Some legislation was occasionally done by this body; a conclusum imperii (so called in distinction from the old recessus imperii of the period before 1663) might slowly (very slowly - for the agents, imperfectly instructed, had constantly to refer matters back to their principals) be achieved; but it rested with the various princes to promulgate and enforce the conclusum in their territories, and they were sufficiently occupied in issuing and enforcing their own decrees. In practice the diet had nothing to do; and its members occupied themselves in "wrangling about chairs" - that is to say, in unending disputes about degrees and precedences.
In the Germanic Confederation, which occupies the interval between the death of the Holy Roman Empire and the formation of the North German Confederation (1815-1866), a diet (Bundestag) existed, which was modelled on the old diet of the 18th century. It was a standing congress of envoys at Frankfort-on-Main. Austria presided in the diet, which, in the earlier years of its history, served, under the influence of Metternich, as an organ for the suppression of Liberal opinion. In the North German Confederation (1867-1870) a new departure was made, which has been followed in the constitution of the present German empire. Two bodies were instituted - a Bundesrat, which resembles the old diet in being a congress of envoys sent by the sovereigns of the different states of the confederation, and a Reichstag, which bears the name of the old diet, but differs entirely in composition. The new Reichstag is a popular representative assembly, based on wide suffrage and elected by ballot; and, above all, it is an assembly representing, not the several states, but the whole Empire, which is divided for this purpose into electoral districts. Both as a popular assembly, and as an assembly which represents the whole of a united Germany, the new Reichstag goes back, one may almost say, beyond the diet even of the middle ages, to the days of the old Teutonic folk-moot.
See R. Schröder, Lehrbuch der deutschen Rechtsgeschichte (1902), pp. 149, 508, 820, 880. Schröder gives a bibliography of monographs bearing on the history of the medieval diet.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)