DAVID, a classical critic of great eminence, was born at Stolpen, in Prussian Pomerania, in the year 1723. Of the early part of his studies little is known, but it appears that he was some time at Schlaff, from which he removed to Königsberg, where he met with the celebrated Kant, whose system has so much engaged the attention of Europe. He afterwards repaired to Göttingen to attend the lectures of Gesner, and to enlarge his knowledge of the Greek language. Some time after this period he formed an acquaintance with Ritter and Berger, whilst he resided at Wittemberg, where he continued about two years. His earliest production was a disputation De Gala Placidia Augusta, daughter of Theodosius, and the sister of Arcadius and Honorius. Under Berger he studied Roman antiquities and eloquence; under Ritter, jurisprudence and history. He relinquished the study of divinity, for which he was at first designed, and prevailed with his parents to allow him to transfer his residence to Leyden, where he arrived with recommendations to many of the learned. He pursued his studies with avidity and zeal, and accompanied Alberti in his visit to the Spa in the year 1750. Hemsterhuis wished to attach him to Holland, urging him to persevere in the study of the law, as affording an additional chance of employment. This advice he thought proper to follow, and published a translation of some works of Theodorus, Stephanus, and other Greek civilians.
In the year 1755 he went to Paris, where Capperonnier, who was at that time keeper of the king's library, received him kindly. He now formed an acquaintance with Dr Musgrave and Mr Tyrwhitt, who were there for the purpose of examining the manuscripts of Euripides. He had also formed the resolution of going to Spain; but Hemsterhuis recalled him, as he needed his assistance as lecturer in the Greek tongue. In 1755, Ruhnkenius took possession of his office, and read an excellent discourse De Graecia Artium et Doctrinarum Inventrice.
About this time he was useful to Ernesti, in his edition of Callimachus; and, in 1761, he succeeded Oudendorp as professor of history and of eloquence, delivering an inaugural oration De Doctore Umbraetio. About a year after this event, Ruhnkenius was offered the chair of Gesner in the university of Göttingen. This offer he however declined; but, on his recommendation, the office was very worthily bestowed upon Heyne.
In 1764 he married an Italian lady, who, about six years afterwards lost both her speech and sight by a stroke of apoplexy. She had two daughters, one of whom was afterwards blind. The desire of Ruhnkenius to do Ernesti a favour, made him turn his attention to the Memorabilia of Xenophon; and he was led to examine with particular attention the treatise of Longinus on the Sublime. Having risen superior to his domestic misfortunes about the year 1772, he pursued his new edition of Velleius Paternus, and he prepared a second edition of his Epistolae Criticae, and a collection of Scholia on Plato. In the year 1766, he published a valuable tract De Vita et Scriptis Longini, in the form of an academical dissertation, to which he prefixed the name of one of his pupils. His Velleius Paternus appeared in 1779, and in 1780 Homer's reputed hymn to Ceres. In 1786, he published the first part of Apuleius, which had been prepared by Oudendorp, and a new edition of his own Timaeus in 1789; and at the same time he collected and published the works of Muretus, in five volumes 8vo.
Both the body and mind of Ruhnkenius were much weakened in consequence of the loss of friends, an attack of the gout, and the misfortunes of the Batavian republic; but he was in some measure relieved by the satisfaction he felt at the dedication of Homer by Wolf, although he was not of that writer's opinion that the works of Homer were written by different authors. He sunk into a kind of stupor on the 14th of May 1798, which in two days put an end to his existence.
His knowledge and learning were unquestionably immense; and he was allowed to be lively, cheerful, and gay, even to an extreme. Many posthumous honours were conferred upon him, and a pension settled on his unfortunate widow. When Whyttenschbach took possession of Ruhnkenius's chair, he delivered a discourse on the early age of Ruhnkenius, which he proposed as an example to the Batavian youth who make the belles lettres their study.