This article seeks to reverse the emphasis, in current studies of material culture, on the materiality of objects as against the properties of materials. Drawing on James Gibson's tripartite division of the inhabited environment into medium, substances and surfaces, it is argued that the forms of things are not imposed from without upon an inert substrate of matter, but are continually generated and dissolved within the fluxes of materials across the interface between substances and the medium that surrounds them. Thus things are active not because they are imbued with agency but because of ways in which they are caught up in these currents of the lifeworld. The properties of materials, then, are not fixed attributes of matter but are processual and relational. To describe these properties means telling their stories.