Meanwhile his worldly affairs prospered; he had become bookkeeper in Bernhard's business. His biographer Kayserling tells us that at this period he was in a fair way to develop into "a true _bel esprit_"; he took lessons on the piano, went to the theatre and to concerts, and wrote poems. During the winter he was at his desk at the office from eight in the morning until nine in the evening. In the summer of 1756, his work was lightened; after two in the afternoon he was his own master. The following year finds him comfortably established in a house of his own with a garden, in which he could be found every evening at six o'clock, Lessing and Nicolai often joining him. Besides, he had laid by a little sum, which enabled him to help his friends, especially Lessing, out of financial embarrassments. Business cares did, indeed, bear heavily upon him, and his complaints are truly touching: "Like a beast of burden laden down, I crawl through life, self-love unfortunately whispering into my ear that nature had perhaps mapped out a poet's career for me. But what can we do, my friends? Let us pity one another, and be content. So long as love for science is not stifled within us, we may hope on." Surely, his love for learning never diminished. On the contrary, his zeal for philosophic studies grew, and with it his reputation in the learned world of Berlin. The Jewish thinker finally attracted the notice of Frederick the Great, whose poems he had had the temerity to criticise adversely in the "Letters on Literature" (_Litteraturbriefe_). He says in that famous criticism:[80] "What a loss it has been for our mother-tongue that this prince has given more time and effort to the French language. We should otherwise possess a treasure which would arouse the envy of our neighbors." A certain Herr von Justi, who had also incurred the unfavorable notice of the _Litteraturbriefe_, used this review to revenge himself on Mendelssohn. He wrote to the Prussian state-councillor: "A miserable publication appears in Berlin, letters on recent literature, in which a Jew, criticising court-preacher Cramer, uses irreverent language in reference to Christianity, and in a bold review of _Poésies diverses_, fails to pay the proper respect to his Majesty's sacred person." Soon an interdict was issued against the _Litteraturbriefe_, and Mendelssohn was summoned to appear before the attorney general Von Uhden. Nicolai has given us an account of the interview between the high and mighty officer of the state and the poor Jewish philosopher: Attorney General: "Look here! How can you venture to write against Christians?" Mendelssohn: "When I bowl with Christians, I throw down all the pins whenever I can." Attorney General: "Do you dare mock at me? Do you know to whom you are speaking?" Mendelssohn: "Oh yes. I am in the presence of privy councillor and attorney general Von Uhden, a just man."