The rigorous response was given by Carnot in his famous Reflections on the Metaphysics of Infinitesimal Calculus, but precisely from the point of view of a finite interpretation: the differential equations are simple 'auxiliaries' expressing the conditions of the problem to which responds a desired equation; but a strict compensation of errors is produced between them such that no differentials persist in the result, since the latter can be arrived at only between fixed or finite quantities.