||R. Isaac Blaser (Reb Itzelle Peterburger; 18371907), Russian rabbi and educator. R. Blaser was one of the foremost disciples of R. Israel Lipkin (Salanter), whose Musar (ethicist) movement he helped develop and lead. In the early 1850s, R. Blaser moved from his native Vilna to Kovno, Lithuania, where he came under the influence of Lipkin. In 1864 he reluctantly accepted the rabbinate of St. Petersburg, hence the name by which he is familiarly known, "Reb Itzelle Peterburger." During this time he wrote halakhic works and responsa, arousing the opposition of the maskilim. He left the rabbinate in 1878, returning to Kovno where he headed the kolel ("advanced talmudical academy"), and sent emissaries throughout the world to gain support for it. He helped to found the yeshivah of Slobodka. About 1891, as the result of bitter controversy concerning the Musar movement, he left the kolel of Kovno and helped to found other such Musar-oriented schools elsewhere. Increasing opposition to the Musar movement (189698) and to R. Blaser, its chief exponent, forced the yeshivah to leave its premises in Slobodka, and it finally became established in Kelm (1898).
In 1904 R. Blaser emigrated to and settled in Jerusalem, where he passed on. His main contribution to the Musar movement was his emphasis on acquiring "fear of the L-rd" (i.e., piety) by means of emotional meditation in works of musar. Unlike other disciples of R. Salanter, who expounded musar intellectually, R. Blaser held that knowledge and conceptualization were inadequate to the task of curbing man's baser instincts. "Fear of the L-rd" could be aroused only by an unsophisticated contemplation of man's physical vulnerability, his moral lowliness, and his punishment for continued disobedience. Since he held that the form of such meditation makes a more lasting impression than the contents, he prescribed the reading aloud of musar texts in a melancholy melody, with frequent periods of weeping. Similarly, his preaching was simple, sad, and usually accompanied by tears. R. Blaser's major literary contribution to the Musar movement, Or Yisrael ("Light of Israel"; 1900), was often reprinted, and for several decades was the only available exposition of musar. R. Blaser here expounded the fundamentals of the Musar approach and presented excerpts from the letters of R. Israel Lipkin, along with evaluations of the teachings of the founders of the Musar movement and of some of its leading personalities.
His major halakhic work is Peri Yizhak ("Fruit of Isaac"); the first volume was published in Vilna in 1881, some 14 years after he had completed writing it. The second volume was published posthumously in 1912. He contributed numerous articles, both on halakhah and musar, to the various rabbinic journals of the day. Much of his writing remained unpublished.