Affordances elude ontology. They have been recognized to play a role in categorization, especially of artifacts, but also of natural features. Yet, attempts to ontologize them face problems ranging from their presumed subjective nature to the fact that they involve potential actions, not objects or properties. We take a fresh look at the ontology of affordances, based on a simple insight: affordances are perceived by agents and may lead to actions, just like qualities are perceived and may lead to observations. We understand perception as a process invoking a quale in an agent. This quale can then be expressed as an action, if it stems from an affordance, or as an observation, if it stems from an other quality. Thus, we see affordances as qualities of the environment, perceived and potentially expressed by agents. We extend our recently proposed ontology of observations to include affordances and show how the parallel between observations (producing values) and affordances (producing actions) provides a simple and powerful ontological account of both.