Millikan and Langer

Millikan's theory of meaning (or theory of intentionality) is the theory that things like the dance of a honeybee or the splash of a beaver's tail have meaning. The signs (the dance or the splash) have a fixed function that they serve. These signs are consumed by other bees and other beavers. The axis on which a bee dances corresponds to the direction in which nectar lies. The tempo at which a bee dances corresponds to the distance of the nectar. The bee can vary the dance to convey different meanings to other bees. To speak anthropomorphically (and hence metaphorically), the bee is telling the other bees where the nectar is and to go get it. A beaver splashing its tail tells other beavers that danger is coming and to take cover. 

Langer provides a theory of 'significance' for art.  She says that art is a symbol for human feelings.  Symbols differ from signs insofar as symbols convey a conception of something, or an idea.  Signs merely refer to an object.  Art forms are similar to languages because they have articulated forms of expression.  Art forms differ from languages because they have no fixed referents for their symbols.