R. Solomon Plessner was a German preacher and Bible commentator; born at Breslau April 23, 1797; died at Posen Aug. 28, 1883. Having lost his father when very young, Plessner had to support his mother and himself. He engaged in business, but found time to study Hebrew, rabbinics, and German, under Wessely's influence. At the age of seventeen Plessner began to study Wessely's Hebrew translation of the Apocrypha, resolving to continue the translation himself. He indeed published at Breslau in 1819 his Hebrew translation of the Apocryphal additions to the Book of Esther, under the title "Hosafah li-Megillat Ester," with a literary-historical introduction. At the same time he became known as an eloquent preacher. Many of his sermons were published, among them his funeral oration on the death of Abraham Tiktin, bearing the Hebrew title "Zeker Ẓaddiḳ li-Berakah" (Breslau, 1821).

Plessner through his sermons was recognized as a warm defender of Orthodox Judaism, and on this account was congratulated by R. Akiva Eger, rabbi of Posen. Soon the conflict arose between the Orthodox and Reform Jews concerning the introduction of the organ into the synagogal services. Plessner naturally fought against the Reform leaders; and as they were the more powerful and began to persecute him, forbidding him through the police to deliver any sermon, he in 1823 settled at Festenberg, a small town in Silesia.

In 1830 Plessner removed to Berlin, where for a short time he was a teacher in the normal school. Although possessing all the knowledge necessary for an Orthodox rabbi, he persistently declined rabbinical office, preferring freedom of speech. He earned a livelihood by preaching every other Saturday in the Berlin bet ha-midrash, continuing at the same time his study of the Apocrypha. In 1832 his "Nozelim Min Lebanon" was published in Berlin. This work consisted of a Hebrew translation of a part of the Apocrypha, with an appendix, entitled "Duda'im," containing exegetical notes, verses in Hebrew and German, and sermons (see Geiger, "Wiss. Zeit. Jüd. Theol." i. 204 et seq.). The following year he was invited to dedicate the new synagogue at Bromberg, for which occasion he composed poems in Hebrew and in German, which were published under the title "Shirim la-Ḥanukkat Bet ha-Tefillah" (Berlin, 1834). In his sermons Plessner adopted the expressions of the most eminent Christian preachers, interspersing his sentences with verses of Schiller and Goethe, and rejecting the derashic or homiletic interpretation of the Bible. In 1834 he began to publish his sermons in yearly volumes under the general title "Belehrungen und Erbauungen" (2d ed. Berlin, 1840, under the title "Religiöse Vorträge"). In 1838 Plessner published his "Dat Mosheh wi-Yehudit," a catechism in twelve parts, preceded by an introduction, on the nature and history of Jewish religious instruction. His oratorical talent is particularly exhibited in his "Miḳra'e Ḳodesh" (Berlin, 1841), a collection of holy-day sermons for the years 1835 to 1839.

A powerful party of antagonists worrying Plessner beyond endurance on account of his outspokenness, he left Berlin and settled at Posen (1843), where he was active as a preacher for forty years. In Posen Plessner preached chiefly at the Neuschul. During his residence in that city he published the following works: "Shay la-Mora" (Posen, 1846), poem in honor of Moses Montefiore; "Shire Zimrah" (Berlin, 1859), poems composed on the occasion of the completion of the publication of the Talmud by the Talmud society Hevrat Shas; "Shire Zimrah" (ib. 1865), Hebrew poems composed for the celebration of the one hundred find fiftieth anniversary of the foundation of the society of mohelim. After Plessner's death two collections of his sermons were published at Frankfort-on-the-Main: "Sabbathpredigten" (1884) and "Festpredigten" (1890).