Scholars have pointed out that Gilman drew upon several different sources to create her synthesis. She borrowed the concept that the realm of production is central to human life and that the workplace is the area of both oppression and liberation from Karl Marx, while applying it to gender, rather than solely class. From Charles Darwin, she used the theory of evolution, and ultimately Social Darwinism, that permeates much of the book. She took the idea that women are object of exchange between men from Thorstein Veblen; and from sociologist Lester Ward, she borrowed the idea that women, rather than men, originated evolution and species. While Gilman drew upon these thinkers for concepts, she did not become part of the movements they inspired.