  Scholem's early work consists of two main areas of research. From 1921 (while still in Germany) until around 1936 Scholem spent untold hours collecting and analyzing every kabbalistic manuscript he could locate. This required traveling to various libraries in Europe. Once he arrived in Palestine he concentrated on the growing collection of Hebrew manuscripts located at the new National Library. This taxing, arduous, and tedious work created a data base for Scholem that would serve his entire career. During this same period he undertook a series of highly critical reviews and essays on previous scholars who dealt with Kabbala, most of which were published in the German-Jewish journal Der Jude and some in Hebrew Keriat Sefer a journal of Jewish Bibliography centered in Jerusalem. These early book reviews constitute an important — and often overlooked—part of Scholem's career. It is here that he distinguishes himself from his predecessors and develops the beginning of his historiographical approach that would only emerge in the next period of his research. His dissertation Das Buch Bahir was published in Leipzig in1923. His first major publications after his dissertation were Kitvei Yad ha-Kabbala, 1930; Perakim le-Toldot sifrut ha-Kabbala,1931; and Bibliographia Kabbalistica, 1927, all bibliographical works examining his discoveries. In addition he published more theoretical studies such as “Kabbalat R. Ya'akov ve-R. Yizhak [ha-Cohen],” 1927; “Ha-Mekubal R. Avraham b. Eliezer ha-Levi” 1925, 26 and “Die Theologie des Sabbatianismus im Lichte Abraham Cardosos” in 1928. Parts of these studies would appear later in more expanded works dealing with various kabbalistic periods. In short, Scholem began his publishing career by first absorbing the entire scope of the history of Kabbala and then slowly putting it together from the earliest period until the latest (Hasidism).