Editing Isaac Barrow (section)

=== Later career ===
==== Work ====
On the [[Restoration (England)|Restoration]] in 1660, he was ordained and appointed to the [[Regius Professor of Greek (Cambridge)|Regius Professorship]] of [[Greek language|Greek]] at the [[University of Cambridge]]. In 1662, he was made professor of [[geometry]] at [[Gresham College]], and in 1663 was selected as the first occupier of the [[Lucasian Professor of Mathematics|Lucasian chair]] at Cambridge. During his tenure of this chair he published two mathematical works of great learning and elegance, the first on geometry and the second on optics. In 1669 he resigned his professorship in favour of [[Isaac Newton]].<ref>For a summary of the Barrow–Newton relationship, see {{cite book |author=Gjersten, Derek |title=The Newton Handbook |year=1986 |location=London |publisher=Routledge & Kegan Paul | pages = 54–55}}</ref> About this time, Barrow composed his ''Expositions of the Creed, The Lord's Prayer, Decalogue, and Sacraments''.  For the remainder of his life he devoted himself to the study of [[divinity]]. He was made a [[Doctor of Divinity]] by Royal mandate in 1670, and two years later Master of [[Trinity College, Cambridge|Trinity College]] (1672), where he founded the library, and held the post until his death.

[[Image:StatueOfIsaacBarrow.jpg|thumb|right|Statue of Isaac Barrow in the chapel of [[Trinity College, Cambridge]]]]
His earliest work was a complete edition of the ''Elements'' of [[Euclid]], which he issued in Latin in 1655, and in English in 1660; in 1657 he published an edition of the ''Data''. His lectures, delivered in 1664, 1665, and 1666, were published in 1683 under the title ''Lectiones Mathematicae''; these are mostly on the metaphysical basis for mathematical truths. His lectures for 1667 were published in the same year, and suggest the analysis by which [[Archimedes]] was led to his chief results. In 1669 he issued his ''Lectiones Opticae et Geometricae''. It is said in the preface that Newton revised and corrected these lectures, adding matter of his own, but it seems probable from Newton's remarks in the fluxional controversy that the additions were confined to the parts which dealt with optics. This, which is his most important work in mathematics, was republished with a few minor alterations in 1674. In 1675 he published an edition with numerous comments of the first four books of the ''On Conic Sections'' of [[Apollonius of Perga]], and of the extant works of Archimedes and [[Theodosius of Bithynia]].

In the optical lectures many problems connected with the reflection and refraction of light are treated with ingenuity. The geometrical focus of a point seen by reflection or refraction is defined; and it is explained that the image of an object is the locus of the geometrical foci of every point on it.  Barrow also worked out a few of the easier properties of thin lenses, and considerably simplified the [[René Descartes|Cartesian]] explanation of the [[rainbow]].

Barrow was the first to find the [[integral of the secant function]] in [[Closed-form expression|closed form]], thereby proving a conjecture that was well-known at the time.

==== Death and legacy ====
Barrow died unmarried in London at the early age of 46, and was buried at [[Westminster Abbey]]. [[John Aubrey]], in the [[Brief Lives]], attributes his death to an opium addiction acquired during his residence in Turkey.

Besides the works above mentioned, he wrote other important treatises on mathematics, but in literature his place is chiefly supported by his sermons,<ref>Isaac Barrow, John Tillotson, Abraham Hill – The works of the learned Isaac Barrow ... Printed by J. Heptinstall, for Brabazon Aylmer, 1700 [https://books.google.com/books?id=ZmVZAAAAYAAJ&dq=isaac+barrow+priest&pg=PA217  Published by DR JOHN TILLOTSON THE LORD ARCHBISHOP OF CANTERBURY ]  {&}   Isaac Barrow – The theological works of Isaac Barrow, Volume 1 [https://books.google.com/books?id=_8ctAAAAYAAJ&dq=isaac+barrow+priest&pg=PA318 The University Press, 1830] {&} Isaac Barrow, Thomas Smart Hughes 1831 – ''The Works of Dr. Isaac Barrow: With Some Account of His Life, Summary of Each Discourse, Notes, &c (1831)''- ''Fourth Volume''  [https://archive.org/stream/worksdrisaacbar01hughgoog#page/n5/mode/2up A.J. Valpy]. Retrieved 1 February 2012</ref> which are masterpieces of argumentative eloquence, while his ''Treatise on the Pope's Supremacy'' is regarded as one of the most perfect specimens of controversy in existence. Barrow's character as a man was in all respects worthy of his great talents, though he had a strong vein of eccentricity.