 Lagrange also applied his ideas to problems of classical mechanics, generalising the results of Euler and Maupertuis.Euler was very impressed with Lagrange's results.It has been stated that "with characteristic courtesy he withheld a paper he had previously written, which covered some of the same ground, in order that the young Italian might have time to complete his work, and claim the undisputed invention of the new calculus"; however, this chivalric view has been disputed.