Abstract We view and interpret the world around us, both natural and cultural, through perceptual and cognitive spectacles of our own construction. The natural sciences claim that their methods, of hypothesis, observation, and experiment, permit something approximating to a true representation of the material reality that surrounds us to be achieved. However, for several decades now, philosophers, historians, and sociologists of science have been pointing to the ways in which our scientific knowledge is socially, culturally, and historically constructed; that is, it offers at best a constrained interpretation of the material world. A first such constraint is provided by the very construction of our brain and the biology of our perceptual processes. To this I would add that brains do not exist in isolation from bodies: how we perceive the world is affected by our hormonal, immunological, and general physiological state.