…Expressions are used here to denote linguistic symbols or words. Expressions meditate between the objects of the existential world and their image in the human mind, thereby making social communication possible. Language therefore plays a dual role. It first serves as a means of communication, thereby making social interaction possible. Secondly, it mediates between the thing and the idea, making advanced reasoning possible.

Therefore every linguistic expression has two counterparts: one is mental belonging to the human mind, reference, the other is existential, belonging to the objective world, referent. Because expression, reference, and referent represent three distinct but closely interrelated realms, namely language, mind, and reality, understanding results from explicating the relationship between the three. It follows that meaning is not simply the property  of linguistic expressions, but rather a property of the relationship among three elements: the idea borne in the mind, the word symbolizing the idea, and the object denoted by the idea.