As a protection for Jewish national unity, which was exposed to the greatest danger after the downfall of the state, there arose and developed, without any external influence whatsoever, an extraordinary dictatorship, unofficial and spiritual. The legislative activity of all the dictators--such as, Rabbi Jochanan ben Zakkai, Rabbi Akiba, the Hillelites, and the Shammaites--was formulated in the Mishna, the "oral law," which was the substructure of the Talmud. Their activity had a characteristic feature, which deserves somewhat particularized description. The laws were not laid down arbitrarily and without ceremony. In order to possess binding force, they required the authoritative confirmation to be found in the Mosaic Books. From these, whether by logical or by forced interpretation of the holy text, its words, or, perchance, its letters, they had to be derived. Each law, barring only the original "traditions," the _Halacha le-Moshe mi-Sinai_, was promulgated over the supreme signature, as it were, that is, with the authentication of a word from the Holy Scriptures. Or it was inferred from another law so authenticated. The elaboration of every law was thus connected with a very complicated process of thought, requiring both inductive and deductive reasoning, and uniting juridical interpretation with the refinements of casuistry. This legislation was the beginning of Talmudic science, which from that time on, for many centuries, growing with the ages, claimed in chief part the intellectual activity of Jewry. The schools and the academies worked out a system of laws at once religious and practical in character, which constituted, in turn, the object of further theoretic study in the same schools and academies. In the course of time, however, the means became the end. Theoretic investigation of the law, extending and developing to the furthest limits, in itself, without reference to its practical value, afforded satisfaction to the spiritual need. The results of theorizing often attained the binding force of law in practical life, not because circumstances ordered it, but simply because one or another academy, by dint of logic or casuistry, had established it as law. The number of such deductions from original and secondary laws increased in geometric progression, and practical life all but failed to keep up with the theory. The "close of the Mishna," that is, its reduction to writing, had no daunting effect upon the zeal for research. If anything, a new and strong impetus was imparted to it. As up to that time the text of the Holy Scriptures had been made the basis of interpretation, giving rise to the most diverse inferences, so the rabbis now began to use the law book recently canonized as a new basis of interpretation, and to carry its principles to their utmost consequences. In this way originated first the "Palestinian Gemara." Later, when the Patriarchate in Palestine was stripped of its glory by