Another former president of the American Economic Association, Georgescu-Roegen, also began to dissent from orthodox economics for reasons not dissimilar to Boulding. In his classic work, The Entropy Law and the Economic Process, Georgescu-Roegen issued a call for the end of the circular flow diagrams used in mainstream thought and textbooks in which the production and circulation process are detached from the physical reality, the scale, of the planet's resources and pollution sinks. He called for greater attention to be given to the second law of thermodynamics – that it be treated as a cornerstone of the mainstream paradigm. Boulding can be seen as addressing this call. Once one considers the possibility that labor can be seen as an intermediate surrogate for more fundamental factors, like know-how, materials and energy, then it is a short step to treat (as Boulding sometimes does) capital as a surrogate for know-how and land as surrogate for material resources and the traditional factors of production, land, labor and capital, are easily rearticulated as know-how, energy and materials. If and when that sort of transformation in thought takes place, professional attention will immediately be focused on the throughput resulting from the production and consumption process. With the rising perception of environmental degradation and the unrelenting thrust of the environmental movement, there is every reason to expect the profession to include throughput as a centerpiece in the production process. Boulding's factors of production accomplish this task.