One crucial point here is that our internal perception of the world around us is greatly influenced by the verbal categories which we use to describe it. A modern urban street scene is wholly man-made and it is only because all the things in it carry individual names, i.e. symbolic labels, that we can recognise what they are. This is true of all human culture and of all human societies. We use language to cut up the visual continuum into meaningful objects and into persons filling distinguishable roles. But we also use language to tie the component elements together again, to put things and persons in relationship to one another. As my very first example about gift giving showed (p. 6), this double function of symbolic action applies to non-verbal as well as to verbal behaviour.

Much the same point is implicit in my contextual definition of signs (p. 14). All signs, and most symbols and signals, cohere together as sets. Meanings depend upon contrast. Red and Green lights mean Stop and Go, but only when they are contrasted one against the other and in their proper setting on a public highway. We recognise a light switch for what it is because we can distinguish it by shape and location from other knobs, such as door handles and window latches, which occur in the same general context. But if we saw the same object lying on the footpath we would not expect it to function as a light switch at all.