p.2 At the heart of Heider's theory lies the distinction between things (physical objects) and the media through which things "reach" the perceiver... Heider argued that things shape media and not vice versa, so the perceptual apparatus must reconstruct things from their effects on media, and ultimately on the senses. Heider termed this reconstructive process in perception attribution, and he argued that it focuses, not on the specifics of the media, but on the dispositional qualities of things, for these qualities shape the media surrounding them. Thus, when we look at a house we say, "I see a house," not "I see sunlight," even though the sunlight is the necessary medium by which we are able to see the house.

p.3 Heider learned from Lewin (himself influenced by the philosopher Ernst Cassier) the value of having a well-organized system of concepts when describing any - and in particular, any psychological - phenomena.

p.6 In the early 1940s, Heider returned to what he had come to recognize as his primary concern: describing the manifold of social relations in more general, theoretically coherent terms. In all his previous analyses of interpersonal behavior - from his early observations of quarreling relatives to his more recent studies of deaf children - Heider felt that he lacked a general framework of concepts with which to describe that behavior. He was convinced that a systematic psychological theory of social relations must start with a well-formed network of concepts applicable to that domain. The breakthrough came when Heider realized that there already existed such a powerful conceptual network - it was commonsense psychology, the system of concepts ordinary people use to describe and understand human behavior. Just as Lewin and Asch before him, Heider recognized that a psychology of social interaction must chart out the subjective concepts and perceptions of the social perceiver, "studying interpersonal relations at the level of their meaning for the participants" (Ickes & Harvey, 1978)... Heider... asserted that a theory of social perception can predict a good deal of human behavior because people's social behavior is based to a large extent on their commonsense concepts of social perception... he made the even bolder assertion that commonsense concepts provide a good starting point for a scientific theory of social behavior.