Of their extensive works but little has been preserved.

What has survived proves that they were gifted with the faculty of applying old precept to modern instance.

They regulated the social and religious affairs of all the Jews in the diaspora.

They improved educational methods, and were pioneers in the popularization of learning.

By a large collection of Case Law, that is, decisions in particular cases, they brought the newer Jewish life into moral harmony with the principles formulated by the earlier Rabbis.