For over 35 years, Information Technology has been dominated by J.C.R. Licklider’s powerful vision of Interactive Computing / Man-Machine Symbiosis. Although this "Human Centered" line of research has been (and continues to be) tremendously productive, Tennenhouse presents the case for opening a "second front" in the research struggle — one that zeros in on the boundary between the physical world, which we live in, and the virtual cocoons, in which we shelter our cherished software. From the Series:CSE Colloquia - 1999