In the present paper the philosophical and mathematical continuity alleged by A. Robinson in Nonstandard Analysis (1966) between his theory and Leibniz’s calculus is investigated. In Section 1, after a brief overview of the history of analysis, we expose the historical, mathematical and philosophical aspects of Leibniz’s calculus. In Section 2 the main technical aspects of nonstandard analysis are presented, and Robinson’s philosophy is discussed. In Section 2.1 we claim the absence of a complete and direct continuity and the only (...) possibility of a conceptual similarity between Leibniz’s and Robinson’s theories, both at the philosophical and at the mathematical level. (shrink)