Stephen A. Forbes (1844-1930) was an American ento- mologist/zoologist who was born, raised and largely educated in northern Illinois. He spent most of his profes- sional career as the director of the Illinois Natural History Survey and as a faculty member and administrator at the University of 1llinois. Early in his scientific career, he stud- ied fish and bird diets by examining the stomach contents of these animals. In 1887, he published his most famous and influential paper, "The lake as a microcosm," which contains one of the earliest formulations of what came to be called the ecosystem. In this paper, Forbes describes a hy- pothetical isolated, small lake as being a microcosm that is in equilibrium. This equilibrium is the result of trophic in- teractions among the organisms in the microcosm that limit the sizes of both predator and prey populations. Forbes believed that natural selection was responsible for limiting the reproductive capacities of predators and prey. Although energy transfer among trophic levels is not the main focus of his paper, Forbes postulated that food (energy) is one of the main factors structuring ecosystems, but he did not explicitly discuss the energetics of his lake microcosm. Forbes' microcosm is based on his studies of the shallow portions of small, glacial lakes in northern Illinois that were dominated by aquatic plants. Today his microcosm would be classified as a palustrine or lacustrine wetland.