Image via Wikipedia//Painting of the Vilna GaonThe term means honorable sage (גאון, גאונים) and was given to the heads of the two Babylonian academies of Sura and Pumbedita. There are no data whatever to show when the title "gaon" originated. Sherira, who is the source for the exact sequence of the Geonim, apparently considers "gaon" an ancient title of the head of the academy, for he says that the Amora Ashi was gaon at Mata Meḥasya (Sura). But Sherira himself begins to use the title consistently only toward the close of the sixth century, "at the end of the Persian rule," when the schools of Sura and Pumbedita resumed their parallel activity after a period of interruption. One is justified, therefore, in assigning to that date the beginning of the period of the Geonim—all the more so as the period of the Saboraim cannot be extended down to the year 689, as Abraham ibn Daud assumes in his historical work, "Sefer ha-Ḳabbalah." According to an old, well-authenticated statement, 'Ena and Simuna, who flourished in the first third of the sixth century, were the last saboraim. The interval between this date and that of the reopening of the schools referred to above, may be included in the period of the Saboraim, and the period of the Geonim may be said to begin with the year 589, when Mar Rab Ḥanan of Isḳiya became gaon of Pumbedita. The first gaon of Sura, according to Sherira, was Mar Rab Mar, who assumed office in 609. The last gaon of Sura was Samuel b. Ḥofni, who died in 1034; the last gaon of Pumbedita was Hai, who died in 1038; hence the activity of the Geonim covers a period of nearly 450 years.
Functions
The Geonim officiated, in the first place, as directors of the academies, continuing as such the educational activity of the Amoraim and Saboraim. For while the Amoraim, through their interpretation of the Mishnah, gave rise to the Talmud, and while the Saboraim definitively edited it, the Geonim's task was to interpret it; for them it became the subject of study and instruction, and they gave religio-legal decisions in agreement with its teachings.
As the academies of Sura and Pumbedita were also invested with judicial authority, the gaon officiated at the same time as supreme judge. The organization of the Babylonian academies recalled the ancient sanhedrin. In many responsa of the Geonim, members of the schools are mentioned who belonged to the "great sanhedrin," and others who belonged to the "small sanhedrin." As may be gathered from the statements of Nathan ha-Babli (tenth century), and from various references in the geonic responsa, the following customs connected with the organization of the academies were observed in the two "kallah" months, Adar and Elul, during which (as in the time of the Amoraim) foreign students assembled in the academy for common study. In front of the presiding gaon and facing him were seated seventy members of the academy in seven rows of ten persons each, each person in the seat assigned to him, and the whole forming, with the gaon, the so-called "great sanhedrin." Gaon Amram calls them in a responsum ("Responsa der Geonim," ed. Lyck, No. 65) the "ordained scholars who take the place of the great sanhedrin."
During the kallah which took place in the month of Adar the gaon laid before the assembly every day a certain number of the questions that had been sent in during the year from all parts of the Diaspora. The requisite answers were discussed, and were finally recorded by the secretary of the academy according to the directions of the gaon. At the end of the kallah month the questions, together with the answers, were read to the assembly, and the answers were signed by the gaon. A large number of the geonic responsa originated in this way; but many of them were written by the respective geonim without consulting the kallah assemblies convened in the spring.
Nathan ha-Babli's account, from which the foregoing statements have been taken, refers only to the kallah months. The remaining months of the year passed more quietly at the academies. Many of the members, including those of the college designated as "sanhedrin," lived scattered in the different provinces, and appeared before the gaon only at the time of the kallah. Nathan designates the permanent students of the academy by the Talmudic term "bene be-rab" (sons of the schoolhouse), in contradistinction to the "other students" that gathered at the kallah. These two classes of students numbered together about 400 at the time when Nathan wrote his account (tenth century). When a resh kallah or any other member of the college died and left a son who was worthy to occupy his father's seat, the son inherited it. The students coming to the academy during the kallah months received support from a fund which was maintained by gifts sent to the academy during the year, and which was in charge of a trust-worthy man. The members sitting in the front rows seem to have drawn a salary.
Two courts were connected with each of the two Babylonian academies. The higher court ("bet din gadol") was presided over by the gaon. It appointed the judges for the districts within the jurisdiction of the respective academies, and was empowered to set aside the verdicts of the several judges and to render new ones. The other court belonging to the academy was under the direction of the ab bet din, and judged minor cases.
Judicial Functions
The geonim occasionally transcended the Talmudic laws and issued new decrees. At the time of the gaons Mar R. Huna at Sura and Mar R. Rabba at Pumbedita (c. 670), for instance, the measures taken in relation to a refractory wife were different from those prescribed in the Talmud. Toward 785 the geonim decreed that debts and the ketubah might be levied on the movable property of orphans. Decrees of this kind were issued jointly by both academies; and they also made common cause in the controversy with Ben Meïr regarding a uniform Jewish calendar.
The gaon was generally elected by the academy, although he was occasionally appointed by the exilarch. The gaon was entirely independent of the exilarch, although the geonim of both academies, together with their prominent members, went every year to render homage to the exilarch. The assembly at which this homage took place was called the "great kallah."
The gaon of Sura ranked above the gaon of Pumbedita, and a sort of court etiquette was developed in which this fact found expression. The gaon of Sura sat at the right hand of the exilarch, while the gaon of Pumbedita sat at the left. When both were present at a banquet, the former pronounced the blessing before and after the meal. The gaon of Sura always had precedence, even if he was much younger than his colleague, and, in writing a letter to him, did not refer to him as gaon, but addressed merely "the Scholars of Pumbedita"; the gaon of Pumbedita, on the other hand, addressed his letters to "the Gaon and the Scholars of Sura." During the solemn installation of the exilarch the gaon of Sura read the Targum to the Pentateuch sections which had been read by the exilarch On the death of the exilarch the gaon of Sura had the exclusive claimto his official income until the election of a new exilarch.
The gaon of Sura evidently owed his superior rank to the ancient reputation of the academy over which he presided; for Sura had been the leading academy of the Babylonian Jews during the period of the Amoraim, first under its founder Rab and his pupil Huna (third century), and then under Ashi (d. 427).
But it was Saadia's activity that lent to this academy unusual luster and an epoch-making importance for Jewish science and its literature. Then, after a long period of decadence, another worthy occupant of the office arose in the person of Samuel b. Ḥofni, the last gaon of Sura.
Significance
The importance of the Geonim in Jewish history is due, in the first place, to the fact that for a number of centuries they occupied a unique position as the heads of their respective schools and as the recognized authorities of Judaism. Their influence probably extended chiefly to the Mohammedan countries, especially northern Africa and Spain; but in the course of time the Jews of Christian. Europe also came under the influence of the Babylonian schools. It was for this reason that the Babylonian Talmud came to be recognized as the basis for religio-legal decisions throughout Jewry and as the principal object of study. Even the facilities offered for such study to the Diaspora were due to the Geonim, since the geonic exposition of the Talmud, with regard to both text and contents, was directly or indirectly the chief aid in comprehending the Talmud. The importance of the period of the Geonim for the history of Judaism is further enhanced by the fact that the new Jewish science, which steadily developed side by side with Talmudic studies, was created by a gaon, and that the same gaon, Saadia, effectively opposed the disintegrating influences of Karaism. The activity of the Geonim may be seen most clearly in their responsa, in which they appear as the teachers of the entire Diaspora, covering in their religio-legal decisions a wide field of instruction.
In the course of the tenth century, however, even before the Babylonian schools ceased with the death of the last gaon, other centers arose in the West from which went forth the teachings and decisions which superseded those of the Geonim. The fixed gifts which the Jews of Spain, the Maghreb, North Africa, Egypt, and Palestine had contributed to the support of the Babylonian schools were discontinued long before and the decadence of these schools was hastened thereby as much as by the internal conflicts to which they were subjected.
Sources:
http://www.jewishencyclopedia.com/view.jsp?artid=68&letter=G&search=geon
http://www.chabad.org/library/article_cdo/aid/115539/jewish/The-Age-of-Scholarship.htm