While the notion of human dependence on Earth's ecosystems reaches to the start of "Homo sapiens" existence, the term 'natural capital' was first coined by E.F. Schumacher in 1973 in his book "Small is Beautiful". Recognition of how ecosystems could provide complex services to humankind date back to at least Plato (c. 400 BC) who understood that deforestation could lead to soil erosion and the drying of springs. Modern ideas of ecosystem services probably began when Marsh challenged in 1864 the idea that Earth's natural resources are unbounded by pointing out changes in soil fertility in the Mediterranean. It was not until the late 1940s that three key authors—Henry Fairfield Osborn, Jr, William Vogt, and Aldo Leopold —promoted recognition of human dependence on the environment.