箴言 14:24的塔木德參照：Avot DeRabbi Natan

Rabban Gamliel the Elder spoke about four kinds of students: the impure fish, the pure fish, the fish from the Jordan, the fish from the Great Sea. What is the impure fish? A child of the poor, who has learned Tanakh, Mishnah, Midrash, Halakhah, and Aggadah, but has no knowledge. What is the pure fish? A child of the rich, who has learned Tanakh, Mishnah, Midrash, Halakhah, and Aggadah, and has knowledge. What is the fish from the Jordan? A scholar who has learned Tanakh, Mishnah, Midrash, Halakhah, and Aggadah, but does not know how to comment upon it. What is the fish from the Great Sea? A scholar who has learned Tanakh, Mishnah, Midrash, Halakhah, and Aggadah, and knows how to comment upon it.