Charles Hall is old enough to remember the shock and exhilaration of coming across the work of M. King Hubbert in the National Academy of Sciences book Energy and Man in 1969 while browsing the bookstore of the University of North Carolina. He was an environmentally sensitive graduate student at the time and had just come across Jay Forrester’s original “Limits to Growth” article in his father’s MIT alumni magazine. He found the concept that all that he saw around him, good and bad, including his tremendous mobility and the availability of graduate education for many, including himself, as well as the mindless development of his beautiful coastal town and the absurd Vietnam war where his friends were serving and being killed, depended on the availability of cheap petroleum which might not last his lifetime. So while his immediate focus was on systems ecology applied to energy use in streams and fish migration, he began to understand (greatly encouraged by his graduate advisor Howard T. Odum) that energy principles applied equally to human endeavors. A postdoc at Brookhaven and Oak Ridge National Laboratories, whose main focus was on nuclear processes, did little to dispel his realization about the importance of energy to most things humans were doing at that time.