This study examines by a meticulous analysis of abundant rabbinic citations the pluralism of the Halakhah in the pre-70 period which stands in contrast to the fixed Halakhah of later periods. The Temple's destruction provoked, for political motives, the initiation of this significant shift, which protracted itself, in developmental stages, for a longer period. The transition from the Tannaitic to the Amoraic era was a consequential turning point on the extended path from flexibility to rigidity in Jewish law.