Muth, Placidus a German Roman Catholic theologian, was born at Poppenhausen, near Schweinfurt, December 30, 1753; received his education at Wtirzburg and Erfurt; then entered, at the age of twenty-four, a convent near Erfurt, and was ordained to the priesthood in 1783. In 1794 he was elected abbot of Bischofsrode and Frankenrode, under the title of Placidus the Second, and also provost at Celle. In 1797, after introducing to the prince-elector of Mentz the idea of a more thorough education in convents, he was appointed archiepiscopal counsellor; but his idea was never carried out, and he went, after the secularization of his convent, to Erfurt, where he was appointed chief counsellor of schools and government, and also director of the gymnasium at that place. He died in 1821. His most important works are, Disquisitio historico-critica in bigamiam Comitis de Gleichen, cujus monumentum est in ecclesia S. Petri Erfordiae; una cum systematica theologiae catholicae synopsi (Erfordiae, 1788, 8vo): — Ueber die Verhaltnisse der Philosophie und Theologie nach Kantischen Grundsitzen (ibid. 1791, 8vo): — Progr. de novis perantiquae Universitatis incrementis, de castris Thuringicis, quae vulgo Comitum de Gleichen dicuntur, nec non de pluribus simulacris Universitati litterarum Erfordiensi dono datis. Particula i et ii (ibid. 1812-13, 4to): — Gedachtnissfeier der Befreiung Pius VII aus der Gefangenschoft zu Fontainebleau und seine Ruckkehr in seine Staaten (ibid. 1814, 8vo). See Doring, Gelehrte theol. Deutschlands, s.v.