Any attempt to explain the archives of Venice and to display their contents, must be preceded by a statement of the main features of the constitution of the Republic upon which the order and the arrangement of the archives is based. The constitution of Venice has frequently been likened to a pyramid, with the Great Council for its base and the Doge for apex. The figure is more or less correct; but it is a pyramid that has been broken at its edges by time and by necessity. The legislative and political body was originally constructed in four groups, or tiers--if we are to preserve the pyramidal simile--one rising above the other. These four tiers were the Maggior Consiglio or Great Council, the Lower House; the Pregadi or Senate, the Upper House; the Collegio, or the Cabinet; and the Doge. The famous Council of Ten and its equally famous Commission, the Three Inquisitors of State, did not enter into the original scheme; they are an appendix to the State, an intrusion, a break in the symmetry of the pyramid. Later on we shall explain their construction and relation to the main body of government. For the present we leave them aside, and confine our attention to the four departments of the Venetian constitution above mentioned. The Great Council, as is well known, did not assume its permanent form and place in the Venetian constitution till the year 1296. At that date the famous revolution, known as the closing of the Great Council, took place. By that act, which was only the final step in a revolution that had been for long in process, those citizens who were excluded from the Great Council remained for ever outside the constitution; all functions of government were concentrated in the hands of those nobles who were included by the Council; the constitution of the Republic was stereotyped as a rigid oligarchy. Previous to the year 1296, a great council had existed, created first in the reign of Pietro Ziani (1172); but this council was really democratic in character, not oligarchic; it was elected each September, and its members were chosen from the whole body of the citizens. Earlier still than the reign of Ziani, the population used to meet tumultuously and express their opinion upon matters of public interest, such as the election of a Doge or a declaration of war, first in the _Concione_ under their tribunes, while Venetia was still a confederation of lagoon-islands; and then in the _Arengo_ under their Doge, when the confederation was centralized at Rialto. But of these assemblies the latter was disorderly and irregular, and the former was of doubtful authority. It is from the closing of the Great Council that we must date the positive establishment of the Venetian oligarchy, and the completion of that constitution which endured for five hundred years, from 1296 till the fall of the Republic in 1797.