individualization and urbanization. Simmel's The Philosophy of Money describes how relationships become more and more mediated by money. Tönnies' Gemeinschaft and Gesellschaft (Community and Society) is about the loss of primary relationships such as familial bonds in favour of goal-oriented, secondary relationships. This idea of alienation can be observed in some other contexts, although the term may not be as frequently used. In the context of an individual's relationships within society, alienation can mean the unresponsiveness of society as a whole to the individuality of each member of the society. When collective decisions are made, it is usually impossible for the unique needs of each person to be taken into account. The American sociologist C. Wright Mills conducted a major study of alienation in modern society with White Collar in 1951, describing how modern consumption-capitalism has shaped a society where you have to sell your personality in addition to your work. Melvin Seeman was part of a surge in alienation research during the mid-20th century when he published his paper, "On the Meaning of Alienation", in 1959. Seeman used the insights of Marx, Emile Durkheim and others to construct what is often considered a model to recognize the five prominent features of alienation: powerlessness, meaninglessness, normlessness, isolation and self-estrangement. Seeman later added a sixth element (cultural estrangement), although this element does not feature prominently in later discussions of his work. In a broader philosophical context, especially in existentialism and phenomenology, alienation describes the inadequacy of the human being (or the mind) in relation to the world. The human mind (as the subject who perceives) sees the world as an object of perception, and is distanced from the world, rather than living within it. This line of thought is generally traced to the works of Søren Kierkegaard in the 19th century, who, from a Christian viewpoint, saw alienation as separation from God, and also examined the emotions and feelings of individuals when faced with life choices. Many 20th-century philosophers (both theistic and atheistic) and theologians were influenced by Kierkegaard's notions of angst, despair and the importance of the individual. Martin Heidegger's concepts of anxiety (angst) and mortality drew from Kierkegaard; he is indebted to the way Kierkegaard lays out the importance of our subjective relation to truth, our existence in the face of death, the temporality of existence and the importance of passionately affirming one's being-in-the-world. Jean-Paul Sartre described the "thing-in-itself"