Even in his literary interests Hertzberg found an adversary in the ungrateful king, for Frederick William, to give one instance, made it so difficult for him to use the archives that in the end Hertzberg entirely gave up the attempt. He found, however, some recompense for all his disillusionment and discouragement in learning, and, Wilhelm von Humboldt excepted, he was the most learned of all the Prussian ministers. As a member of the Berlin Academy especially, and, from 1786 onwards, as its curator, Hertzberg carried on a great and valuable activity in the world of learning. His yearly reports dealt with history, statistics and political science. The most interesting is that of 1784: _Sur la forme des gouvernements, et quelle est la meilleure_. This is directed exclusively against the absolute system (following Montesquieu), upholds a limited monarchy, and is in favour of extending to the peasants the right to be represented in the diet. He spoke for the last time in 1793 on Frederick the Great and the advantages of monarchy. After 1783 these discourses caused a great sensation, since Hertzberg introduced into them a review of the financial situation, which in the days of absolutism seemed an unprecedented innovation. Besides this, Hertzberg exerted himself as an academician to change the strongly French character of the Academy and make it into a truly German institution. He showed a keen interest in the old German language and literature. A special "German deputation" was set aside at the Academy and entrusted with the drawing up of a German grammar and dictionary. He also stood in very close relations with many of the German poets of the time, and especially with Daniel Schubart. Among the German historians in whom he took a great interest, he had the greatest esteem for Pufendorf. He was equally concerned in the improvement of the state of education. In 1780 he boldly took up the defence of German literature, which had been disparaged by Frederick the Great in his famous writing _De la litterature allemande_. Hertzberg's frank and honourable nature little fitted him to be a successful diplomatist; but the course of history has justified many of his aims and ideals, and in Prussia his memory is honoured. He died at Berlin on the 22nd of May 1795.