 Born in Wales in 1848, Emily Elizabeth Constance Jones matriculated at Girton College, Cambridge University’s newly established women’s college, in 1875. She studied for the Moral Sciences Tripos under Henry Sidgwick, James Ward and John Neville Keynes, receiving a “First Class”, Sidgwick being among her examiners. (Her brothers’ education took priority over her own, delaying her entry into the academy and occasioning subsequent interruptions.) It was due to the interventions of Sidgwick and Ward that Jones, fluent from childhood in both German and French, was offered to complete, upon graduation, the remaining half of a translation of Hermann Lotze’s massive Mikrocosmos, left unfinished by Elizabeth Hamilton (the recently deceased daughter of Sir William Hamilton). Jones later went on to become Sidgwick’s literary executor. Her research in philosophical logic dates from 1884, when she began her career at Girton College as Resident Lecturer in Moral Sciences and was called upon to teach courses in logic; she later became Vice-Mistress and, subsequently, Mistress of Girton. During this period, Jones wrote a number of introductory logic texts, some of which went through several printings. By 1890, in her Elements of Logic as a Science of Propositions, whose main philosophical themes are summarized in “The Import of Categorical Propositions” (Jones 1893a), she developed her “law of significant assertion”—the “new law of thought” which would become the focus of her subsequent work in philosophical logic, culminating in the eponymously-titled monograph, published by Cambridge University Press in 1911. During the same period Jones also published numerous papers, as well as an introductory text (Jones 1909), in ethics. While her work in this area was primarily devoted to the exposition, interpretation and defense of Sidgwick’s work, she arguably broke new ground in her attempt at resolving Sidgwick’s dualism of practical reason. Jones was also a capable administrator. When she became Mistress of Girton in 1903, the college was £43,000 in debt (equivalent to £5,185,069 in 2020); at the time of her retirement in 1916, the debt had been paid off and funds had been raised to finance several fellowships. Her death in 1922 was marked by the appearance of substantial obituaries in Mind, Proceedings of the Aristotelian Society and The International Journal of Ethics (now Ethics).