What is the theme in Fable by Octavio Paz?

Related to the idea of the tension between reason and imagination is the concept of the limitations of language. Again it seems dangerous and counter to the spirit of "Fable" to try to tease out a single "meaning" about the nature of language in its lines to explain what is being expressed. Paz seems to be pointing to the idea that there is a gap between an experience and the expression of it in language. Or perhaps he is saying that human experience cannot be expressed in certain types of language. He talks about the unity of the "word."