Johann Christoph Wolff deserves a post, or several post, but this one is about R. Moshe Hagiz.
Wolff is famed for his monumental four-volume bibliographic work Bibliotheca Hebraea (1715-1733). Containing more than 5,000 pages, the nucleus of this work comes from Wolff's having read R. Shabbetai (Meshorer) Bass's bibliographic Siftei Yeshanim (on him and this work, see here) and having access to the great David Oppenheimer collection (see here. The third and fourth circumstances were his familiarity with earlier Hebrew bibliographic works by Christian scholars, and his personal relations with living rabbinic scholars.
This post concerns the last point. R. Moshe Hagiz became acquainted with him while living in Altona. The introduction to his Mishnas Chachomim discusses the meaning of an old custom of substituting the Tetragrammaton with three yuds, like this: ייי In reference to that, he writes of visting the great library at the home of יוחנן קרישטוף וואלף, and he was much impressed with the man and with his collection.
As you can see, he refers to Yochanan Christoph Wolf, the doktor-professor, the famed preacher of Hamburg, God prolong his life with good and sweet times. In God's goodness, he [ie, R. Hagiz] was able to visit his library and he saw thousands upon thousands of volumes in many languages; not only printed works, but there were many ancient Hebrew manuscripts!
The entry ends (pg. 755), with the following appraisal of the rabbi:
Which seems to mean, simply, From our talks I know that he is an intelligent and straight man and very expert in Jewish law and history and also in various languages."