Wessely wrote also several important works on questions in Hebrew
grammar and philology. The chief of them is _Lebanon_, two parts of
which appeared, each separately, under the title _Gan Na'ul_ ("The
Locked Garden", Berlin, 1765); the other parts never appeared in print.
They bear witness to their author's solid scientific attainments, and it
is regrettable that their value is obscured by his style, diffuse to the
point of prolixity. Besides, Wessely contributed to the German
translation of the Bible, and to the commentary on the Bible, both, as
mentioned before, works presided over by Mendelssohn, to whom he was
attached by the tie of admiring friendship.

Wessely's chief distinction, however, was his firm character and his
love of truth. His high ethical qualities were revealed notably in his
pamphlet _Dibre Shalom wa-Emet_ ("Words of Peace and Truth,"
Berlin, 1781), elicited by the edict of Emperor Joseph II ordering a
reform of Jewish education and the establishment of modern schools for
Jews. Though well on in years, he yet did not shrink from the risk of
incurring the anger of the fanatics. He openly declared himself in favor
of pedagogic innovations. With sage-like modesty and mildness, the poet
stated the pressing need for adopting new educational methods, and
showed them to be by no means in opposition to the Mosaic and Rabbinic
conception of the Jewish faith. In the name of _Torat ha-Adam_, the
law for man as such, he set forth urgent reforms which would raise the
prestige of the Law as well as of the Jews. He hoped for civil liberty,
the liberty the Jews were enjoying in England and in the Netherlands.
However, this courageous course gained for him the ban of the fanatics,
the effect of which was mitigated by the intervention of the Italian
Rabbis in favor of Wessely. On the other hand, it made him the most
prominent member of the Meassefim circle; he was regarded as the master