Empire, and he ruled over it with full sovereignty. Therefore, he said, there was no legal or political barrier to letting him rule it as a kingdom. Frederick was aided in the negotiations by Charles Ancillon. Frederick crowned himself on 18 January 1701 in Königsberg. Although he did so with the Emperor's consent, and also with formal acknowledgement from Augustus II the Strong, Elector of Saxony, who held the title of King of Poland, the Polish-Lithuanian Diet (Sejm) raised objections, and viewed the coronation as illegal. In fact, according to the terms of the Treaty of Wehlau and Bromberg, the House of Hohenzollern's sovereignty over the Duchy of Prussia was not absolute but contingent on the continuation of the male line (in the absence of which the duchy would revert to the Polish crown). Therefore, out of deference to the region's historic ties to the Polish crown, Frederick made the symbolic concession of calling himself "King in Prussia" instead of "King of Prussia". His royalty was, in any case, limited to Prussia and did not reduce the rights of the Emperor in the portions of his domains that were still part of the Holy Roman Empire. In other words, while he was a king in Prussia, he was still only an elector under the suzerainty of the Holy Roman Emperor in Brandenburg. Legally, the Hohenzollern state was still a personal union between Brandenburg and Prussia. However, by the time Frederick crowned himself as king, the emperor's authority over Brandenburg (and the rest of the empire) was only nominal, and in practice it soon came to be treated as part of the Prussian kingdom rather than as a separate entity. His grandson, Frederick the Great, was the first Prussian king formally to style himself "King of Prussia" (from 1772 onwards). Frederick was a patron of the arts and learning. The Prussian Academy of Arts in Berlin was founded by Frederick in 1696, as was the Academy of Sciences in 1700, though the latter was closed down by his son as an economic measure; it was reopened in 1740 by his grandson, Frederick II. Frederick also appointed Jacob Paul von Gundling as Professor of History and Law at the Berlin Knights Academy in 1705, and as historian at the Higher Herald's Office in 1706. Frederick died in Berlin in 1713 and is entombed in the Berliner Dom. His grandson, Frederick the Great,