Heinrich Friedrich Wilhelm Geseius (1786–1842) was a German orientalist, lexicographer, and Bible scholar. Born at Nordhausen, he taught in several German towns and was appointed professor of theology at the University of Halle in 1811. He wrote a number of studies on Semitic languages. Gesenius' main field of interest was the scientific investigation of biblical Hebrew based on comparison with other Semitic languages and his studies remained basic for subsequent research. His work was the first in a field of research that freed the study of Hebrew from theological considerations. His most important contributions to the knowledge of Hebrew language and grammar are: (1) Hebraeisch-deutsches Handwoerterbuch..., in two volumes (Leipzig, 1810–12); an improved edition "Hebraeisches und chaldaeisches Handwoerterbuch ueber das Alte Testament" (Leipzig, 1815; after the tenth edition aramaeisches was substituted for chaldaeisches). The book has appeared in German in 16 editions. The 16th edition (1915) was reprinted several times and was translated into English (A Hebrew and English Lexicon of the Old Testament, ed. F. Brown, S. R. Driver, and Ch. A. Briggs, 1907; corrected impression 1952); (2) Thesaurus philologicus criticus linguae Hebraeae et Chaldaeae veteris testamenti (started to appear in 1829 but was completed only posthumously by his pupil E. Roediger, in 1858). In this dictionary, Gesenius drew on talmudic sources and quotes Jewish Bible commentators such as Rashi, R. Abraham ibn Ezra, and R. David Kimhi; (3) ebraeische Grammatik (Halle, 1813), a Hebrew grammar which appeared in German in 29 editions and was also translated into English (Gesenius' Hebrew Grammar, ed. A. E. Cowley, 1910); (4) ebraeisches Lesebuch ("A Hebrew Reader," Halle, 1814); (5) eschichte der hebraeischen Sprache und Schrift ("A History of the Hebrew language and script," Leipzig, 1815); (6) Ausfuehrliches grammatisch-kritisches Lehrgebaeude der hebraeischen Sprache mit Vergleichung der verwandten Dialekte (Leipzig, 1817). In it, he explained his scientific linguistic system based on comparative Semitic philology. Gesenius wrote one exegetical work, a commentary (together with a translation) on Isaiah, in three volumes (Leipzig 1820–21, 1829).