A Book’s History -- A Book in Search of a Discipline (1801–1860) -- Several Disciplines and a Book (1860–1901) -- Algebraic Equations, Quadratic Forms, Higher Congruences: Key Mathematical Techniques of the Disquisitiones Arithmeticae -- The Disquisitiones Arithmeticae and the Theory of Equations -- Composition of Binary Quadratic Forms and the Foundations of Mathematics -- Composition of Quadratic Forms: An Algebraic Perspective -- The Unpublished Section Eight: On the Way to Function Fields over a Finite Field -- The German Reception of the Disquisitiones Arithmeticae: Institutions and Ideas -- A Network of Scientific Philanthropy: Humboldt’s Relations with Number Theorists -- ‘O ??ò?’ A??????í???: The Rise of Pure Mathematics as Arithmetic with Gauss -- Complex Numbers and Complex Functions in Arithmetic -- From Reciprocity Laws to Ideal Numbers: An (Un)Known Manuscript by E.E. Kummer -- Elliptic Functions and Arithmetic -- Numbers as Model Objects of Mathematics -- The Concept of Number from Gauss to Kronecker -- On Arithmetization -- Number Theory and the Disquisitiones in France after 1850 -- The Hermitian Form of Reading the Disquisitiones -- Number Theory at the Association française pour l’avancement des sciences -- Spotlighting Some Later Reactions -- An Overview on Italian Arithmetic after the Disquisitiones Arithmeticae -- Zolotarev’s Theory of Algebraic Numbers -- Gauss Goes West: The Reception of the Disquisitiones Arithmeticae in the USA -- Gauss’s Theorems in the Long Run: Three Case Studies -- Reduction Theory of Quadratic Forms: Towards Räumliche Anschauung in Minkowski’s Early Work -- Gauss Sums -- The Development of the Principal Genus Theorem.