"Seeing is believing"?; "I'm from Missouri, show me"; "The proof of the pudding is in the eating"; Classification: How we make sense of the World. These time-honoured sayings encompass two of the ways humans figure out what is going on by their and others' observations; and by reflecting on the multitude of everyday practices by which we constantly negotiate our relationships with our built and social environments – principally at work, in the home, on the street and in our dream-work. Making sense also entails making and forming concepts of two kinds: classification of objects, material and social, and creating concepts that select from the welter of experiences that would otherwise remain random and confusing. Apart from those who think and write about concepts and produce them intentionally, ordinary concept formation is mostly unacknowledged by producers. Concepts are extrapolated from elements of the cultural climate as well as more enduring world-views. Without them neither observation nor practice would take shape in our collective understanding of the social world and of material objects.