small relative to the natural sources but sufficient to produce large effects in the resulting patterns and processes." Ecological engineering as a practical field was developed by his former graduate student Bill Mitsch, who started and continues to edit the standard journal in the field and helped to start both international and U.S. societies devoted to ecological engineering, and has written two textbooks on the subject One of Odum's last papers was his assessment of ecological engineering that was published in the journal Ecological Engineering in 2003, a year after Odum died. General systems theory In 1991, Odum was elected the 30th president of the International Society for the Systems Sciences, formerly named the International Society for General Systems Research. He presented many papers on the general systems theory at its annual conferences, and edited the last published General Systems Yearbook. The second, revised edition of his major lifework was retitled Ecological and General Systems: An Introduction to Systems Ecology (1994). Some of his energy models and simulations contained general systems components. Odum has been described as a "technocratic optimist", and his approach was significantly influenced by his father, who was also an advocate of viewing the social world through the various lenses of physical science. Within the processes on earth, Odum (1989) believed humans play a central role: he said that the "human is the biosphere's programmatic and pragmatic information processor for maximum performance". Publications Odum wrote around 15 books and 300 papers, and a Festschrift volume (Maximum Power: The Ideas and Applications of H. T. Odum, 1995) was published in honor of his work. Odum was also honored by the journal Ecological Engineering for his contributions to the field of ecological engineering and general ecology in recognition of his 70th birthday. The publication included over 25 letters from distinguished scientists from all over the world including Mitsch (lead editorial), John Allen, Robert Ulanowitcz, Robert Beyers, Ariel Lugo, Marth Gilliland, Sandra Brown, Ramon Margalef, Paul Risser, Eugene Odum, Kathy Ewel, Kenneth Watt, Pat Kangas, Sven Jørgensen, Bob Knight, Rusong Wang, John Teal, Frank Golley, AnnMari and Bengt-Owe Jansson, Joan Browder, Carl Folke, Richard Wiegert, Scott Nixon, Gene Turner, John Todd, and James Zuchetto. Books 2007, Environment, Power and Society for the Twenty-First Century: The Hierarchy of Energy, with Mark T. Brown, Columbia University Press. 2001, A Prosperous Way Down: Principles and Policies, with Elisabeth C. Odum, University Press of