The Hebrew term and title is applied to exceptional Talmudic scholars among OrthodoxJews. It is used among English speaking and Yiddish speaking Orthodox Jews to identify, as a type of mark of honor, those who have been blessed with greater mental and intellectual capabilities than the average intelligent Torah scholar.
Illui is a noun (meaning "above," "elevation," "going up," or "best" from the root meaning "on top" or "above" ) derived from the Hebrew and Yiddish.
Recognition of genius
It is considered a mark of honor and excellence for a Talmudic scholar to be recognized as an illui and to be described and called as such by his peers. It indicates that he is regarded as having extraordinary intelligence and mental capacity, necessary for the most serious, advanced and complex Talmudic learning and Torah study.
In common terminology, an illui would be someone who has an extraordinarily high "IQ" as recognized from early childhood as a child prodigy by rabbis and Torah scholars who have a keen eye to recognize the qualities of excellence in budding young Torah scholars.
Haredi and Hasidic Jews are very familiar with this term, and if a scholar that they are familiar with has been known to have been called an illui they will regard it as a great honor for that individual as well as for his family, teachers and those with whom he associates. In Orthodox, Haredi and Hasidic circles, the term illui is applied to males only, as women are not obligated in Torah study to the same degree that men are required to devote much of their early life to serious and intense Torah studies, also referred to as Torah learning.
There are some Judaic mystical traditions that explain how and why illuim are different. One explanation attributes it to an "Angel's Slap":
An intriguing legend from the Talmud and Midrash describes how a child, while still in its mother's womb, is taught the entire Torah to the glow of a supernatural lamp that allows it to see to the ends of the earth. It is only at the moment of birth that an angel appears and imposes upon it an oath to live a righteous life, and then slaps the youngster on the mouth or the nose, causing it to forget all that it has learned.
The angel's smack in the Talmudic legend produces total amnesia for all, but in the Greek theory of "anamnesis" the souls quaff varying quantities of the oblivion-inducing potion. The clever souls drink no more than they have to, which makes for an easier job of learning and recalling during their coming lives. Only the foolish and short-sighted souls make the mistake of rashly and greedily gulping down excessive doses, dooming them to lives of ignorance and dull-wittedness.
Furthermore, the Jewish world had its share of child prodigies and geniuses who mastered the Talmud at a tender age (such a person is known in Hebrew as an "Illui"). This phenomenon could be ascribed to the soul's evading the angel's slap, whether by accident or design.
The usage of the term is also used with caution in terms of its practical implications for the one who holds it. For example, Jonathan Rosenblum, a notable Haredi commentator has cautioned that:
Talmudic prodigies exist. But there is a certain type of wisdom that only comes with age and life experience, no matter how brilliant a person may be. That is why the leaders of the Torah world are inevitably drawn from the ranks of the ziknei hador ("elders of the generation"). If the first adjective still used to describe a person is ilui, he is probably not yet ready for leadership.
The students in the yeshibah were grouped according to the cities whence they came. Thus one would be known as "Itzel der Kovner" (Isaac of Kovno) and another as "Getzil der Warsawer." Some received the title "'illui" (= "the excellent") or "matmid" (= "diligent student"), such a one being known, for example, as "Der Kovner 'Illui" or "Der Lomzer Matmid," assuming that only one from a town was so designated. The title was given by the general consent of the students. They studied singly or in pair.
Recognition in all denominations
The term illui has widespread usage in all Jewish denominations. Rabbi Eric Yoffie, President of the Union for Reform Judaism in the United States states that: "... It was the illui - the truly superior student - who would devote his life to study, while others would return to full-time employment. Indeed, even when the great yeshivot of Eastern Europe were at their height, the number of students was relatively modest and smaller than the number of full-time Torah students in Israel today..." (writing for Union for Reform Judaism, 2008.)
Rabbi Louis Jacobs (1920 - 2006), of the Conservative Judaism-Masorti Movement, has been described as being: "...Identified by his teachers as an ilui, a talmudic genius -- renowned even then for his prodigious memory and sharp intellect -- he went on to study at the Gateshead Kollel, which at that time was considered the Oxford of rabbinical academies..."
The Vilna Gaon (Rabbi Eliyahu ben Shlomo Zalman) (1720 - 1797): "...Recognized early in life as an illui (child prodigy), at the early age of six, he gave a complicated sermon (drasha) in the Synagogue of Vilna amazing the listeners by answering questions with great depth. This, in a city known worldwide for its scholarship..."
Abraham Mapu (Hebrew writer) (1808 - 1867): "...His early education in Bible and Talmud was received at the heder, on leaving which, at the age of twelve, he continued the study of the Talmud in private, and was so successful that he soon acquired the name of "'Illui" (Friedberg, "Zikronot," in "Hausfreund," i. 22)..." (Jewish Encyclopedia)
Regarding Rabbi Menachem Ziemba (1883 - 1943) and his son: "...In 5684 Reb Menachem lost his son, Moshe Yehudah Aryeh, at the age of 19. The young boy was already known as an illui (genius) in the same mold as his father..."
Rabbi Dovid Lifshitz (1906 - 1993): "...Born in Minsk, Russia, in 1906, Rabbi Lifshitz was recognized at a very young age as an "illui," a child prodigy in Jewish studies. At the age of 12, he coedited a volume of commentary on the Bible..." (Obituary in the New York Times, 1993)
Rabbi Shlomo Carlebach, the musician, (1925 - 1994): "...Shlomo was a child prodigy scholar called an illui in Hebrew. He had the Torah (Bible) half memorized by the time he was a scant five years old and had an insatiable love of learning Judaism. He was carefully guarded and received treatment reserved for royalty..."