BARROW, ISAAC. - English Protestant mathematician and theologian, b. in London in 1630, d. there on 4 May 1677. He spent many years abroad, studying in France, Italy, Turkey, Germany, and Holland. In 1660 he was appointed professor of Greek; in 1662 professor of mathematics in London, and in 1663 at Cambridge, where he had NEWTON as a pupil, whose superior genius he humbly recognized by ceding to him his chair in 1669. His mathematical and geometrical works, continuing the studies of Kepler and foreshadowing those of Newton, consist of an edition of Euclid, Apollonius, and Theodosius, and the *Lectiones opticae geometricae*. From his uncle, the bishop of St. Asaph, he received a small benefice in Wales, and from the bishop of Sarum a prebend in the cathedral of Salisbury. In 1670 he was made doctor of theology and in 1672 rector of Trinity College. Disappointed by the unfavourable reception of his scientific works, after 1670 he devoted himself solely to the study of theology.
His most important controversial work was the treatise *On the Pope's Supremacy* (1680), written in a clear and vigorous style, woven with logical arguments rather than polemical motives, in which his calm temperament and spirit of broad Christian charity kept him far from the usual anti-papal invective that characterized the disputes of the time. Another work of the same kind, in favour of the dogmatic positions of the Anglican Church, was the *Exposition of the Creed, Decalogue and Sacraments*. Barrow was highly renowned, more among posterity than among his contemporaries, as a preacher; “the prince of preachers,” as Charles II, for whom he served as chaplain, called him, “because he exhausted every subject and left nothing new for those who came after him to say.”
His *Sermons*, published posthumously by his literary executor Tillotson (4 vols. in-folio), bear witness to a prodigious inventive fertility. “Masterpieces of their kind,” Locke called them. The habit of mathematical studies strengthened in Barrow that conceptual clarity and mental rigour which make each of his sermons the demonstration of a theorem. The apparent fluency of style and ease of expression are the fruit of unremitting and prolonged labour. Certainly Barrow addresses reason more than sentiment; his sermons, always eloquent and often elevated, are however marred by prolixity, though sustained by an extreme virility of tone and entirely free from any affectation.