That part of universal arithmetic which relates to the changes of variable quantities, and which is known under the titles—Fluxions, The Higher Calculus, The Infinitesimal Calculus, The Theory of Functions, has been divided into two branches, called respectively the Differential and the Integral Calculus; the one of these being regarded as the converse of the other; and every problem connected with variation has been supposed to require either or both of the processes known as differentiation and integration.