The purpose of this dissertation is to study the life and work of R. Eliezer b. Nathan of Mayence (1090-1170) with particular references to Eben Haezer, his magnum opus, as a source for the political, social, economic, and religious history of the time. While R. Eliezer was well known to his contemporaries as well as to the generations that immediately followed him, his influence became somewhat vitiated over the course of the years. He was overshadowed by many of his contemporaries whose works won for them much wider acceptance than what was granted to him. This was particularly so for his contemporaries in France, the Tosafort, who found their interpretations and novellae studied almost as much as the Talmud itself. R. Eliezer on the other hand, just as much a giant in his own time, was gradually forgotten, except for the passing references in the later literature. The very paucity of available texts of Eben Haezer was itself proof of the limitations of his later influence.1