 Complete the following phrase:  In 1766 Valckenaer succeeded Hemsterhuis in the Greek chair. The intimacy between the two colleagues was only broken by Valckenaers death in 1785, and stood the test of common candidature for the office an important one at Leiden of 12th Librarian of Leiden University, in which Ruhnken was successful. Ruhnkens later years were clouded by severe domestic misfortune, and by the political commotions which, after the outbreak of the 