A most fascinating aspect of calculus is its power to surprise even an experienced mathemat ician. Just when it appears that all ideas, results and connections have been discovered and thorough ly analyzed, the horizon suddenly broadens and somebody cries the familiar "eureka". The reason could be either a new result, a simpler way to prove an existing theorem, or a previously missed connection between different ideas. This potential for enrichment is second to none, and it reaffirms the unparalleled educational value of this area of mathematics.
© 2002 The Mathematical Association of America
A. Aksoy, M. Martelli: “Mixed Partial Derivatives and Fubini’s Theorem,” College Mathematics Journal of MAA, Vol.33, 2002, pages 126-130.