This four-volume work represents the most comprehensive documentation and study of the creation of general relativity. It contains the direct facsimile, transcript and explanation of and comments on the Einstein Zurich Notebook as written in 1912. Additional sources from Einstein and others are presented here in translation for the first time. The volumes offer detailed commentaries and analyses of these sources that are based on a close reading of these documents supplemented by interpretations by the leading historians of relativity.