In his later years Benjacob was one of the leaders and representatives of the Jewish community of Vilnius, and took an active part in all communal affairs. In his correspondence with Isaac Bär Lewinsohn, which is partly published in "Ha-Kerem" (pp. 41–62, Warsaw, 1888), Benjacob throws much light on the condition of the community in the beginning of the second half of the 19th century, and especially on the lamentable condition of the Rabbiner Schule (Rabbinical Seminary) which the government established there and in Jitomir in 1848, and closed in 1873. Benjacob himself was originally destined to be one of the teachers of the Vilnius Seminary, but never filled the position, and later he became one of the severest critics of that institution. These letters are also interesting on account of the idea they give of the perplexities of the old Maskilim of the Mendelssohnian school in Russia, like Benjacob, who were being swept aside by the younger generation which had the advantage of a Russian training. He could not speak Russian, and most of the representatives of the community suffered from the same disability, excepting a few merchants who cared little for the fate of the seminary; the older members were at a great disadvantage when pitted against the young students, who could gain whatever they desired from the authorities on account of their correct Russian accent.