I see with much pleasure that you are working on a large work on the integral Calculus [ … ] The reconciliation of the methods which you are planning to make, serves to clarify them mutually, and what they have in common contains very often their true metaphysics; this is why that metaphysics is almost the last thing that one discovers. The spirit arrives at the results as if by instinct; it is only on reflecting upon the route that it and others have followed that it succeeds in generalising the methods and in discovering its metaphysics.
Pierre-Simon Laplace (1792) in: I. Grattan-Guinness Convolutions in French Mathematics, 1800-1840:From the Calculus and Mechanics to Mathematical Analysis and Mathematical Physics. Vol.1: The Setting, Springer Science & Business Media, 1 July 1990, p. 139.