Introduction; Part I. The Calculus as Algebra: Introduction; 1. The development of Lagrange's ideas on the calculus: 1754-1797; 2. The algebraic background of the theory of analytic functions; 3. The contents of the functions; 4. From proof-technique to definition: the pre-history of Delta-Epsilon methods; Conclusion; Appendix; Bibliography; Bibliography: 1966-present; Part II. Selected Writings: 5. The mathematician, the historian, and the history of mathematics; 6. Who gave you the Epsilon? Cauchy and the origins of rigorous calculus; 7. The changing concept of change: the derivative from Fermat to Weierstrass; 8. The centrality of mathematics in the history of Western thought; 9. Descartes and problem-solving; 10. The calculus as algebra, the calculus as geometry: Lagrange, Maclaurin, and their legacy; 11. Was Newton's calculus a dead end? The continental influence of Maclaurin's Treatise of Fluxions; 12. Newton, Maclaurin, and the authority of mathematics; 13. Why should historical truth matter to mathematicians? Dispelling myths while promoting maths; 14. Why did Lagrange 'prove' the parallel postulate?; Index; About the author.