In 1997, a collection of twenty personal perspectives from eminent chemists was published in Pure and Applied Chemistry to mark the centenary of physical organic chemistry . This Symposium in Print, entitled Physical Organic Chemistry in the 21st Century (POC21C), was organized by the IUPAC Commission on Physical Organic Chemistry, which was chaired at that time by Tom Tidwell, who contributed a historical prologue in which he suggested Stieglitz’s 1899 proposal of carbocations as reaction intermediates as (unwittingly) having given birth to the discipline. The principal authors were Edward Arnett, Daniel Bellus, Ron Breslow, Fulvio Cacace, Jan Engberts, Marye Anne Fox, Ken Houk, Keith Ingold, Alan Katritzky, Ed Kosower, Meir Lahav, Teruaki Mukaiyama, Oleg Nefedov, George Olah, John Roberts, Jean-Michel Savéant, Helmut Schwarz, Andrew Streitwieser, Frank Westheimer, and Akio Yamamoto. Tidwell noted that, whereas they were not all known as physical organic chemists, yet they had all used the tools of this discipline in their work and were able to comment upon the utility of physical organic chemistry for the practice of other areas of chemistry as well. The theme that ran through all the essays was that the future of the field lay in an interdisciplinary approach, that physical organic chemists would use all the tools available to them, and that they would not be fettered to narrow views.