Do not be fooled by those who dismiss this as a mere curiousity in Foucault's oeuvre. This difficult work is absolutely essential for understanding his central concept of 'discourse'. All of his works are better understood after a careful reading of this difficult work; this is true even for the later 'geneaological' works.
The Conclusion of this book (Chapter V) is perhaps the most interesting. Foucault appears to be corresponding with an undisclosed someone, wether with himself as a self critique, or with a critic. I won't put asside the possibility he is coversing with someone from the Tavistock Inst.; as Tavistock Publications Lim. was the first place of translation for this text. If he had not suceeded, in his archaeology of knowledge, an undermining of structuralism, with the thesis on human discourse, then perhaps it is because of a lack of conviction on part of this "someone" or on part of himself.
Understanding the implication of Foucault's thought process from a first read requires a refflective reader and in many ways requires a far-reaching mind from the start. This work is composed of a terminal plethora of architectures and teleological plethoras of exemplifications from science and history. Economics, stats, documents, records, and items from all discourses are examined and presented as artifacts of discursive knowledge. The Archeaology itself is the thematic for the Archive, and the archive is the preservatory of knowledge, that such discursive knowledge is preserved is archaeology. Foucault's task then is to undermine the archives of knowledge and present that knowledge back upon the structural framework of rational discourse. With observational power and radical ability, Foucault goes beyond the framework and invisibly subordinates it's needs to be observed and it's intention to be ritcheous (ritcheous in all that it accounts for, and ritcheous of the observer.) From the most primordial archean, to the revival of the primal archaic state, to the archaology of all knowledge, Foucault shows that in a way discourses built upon historical facts are like artifacts themselves. Here in the conclusion we see that the problematic of language (langue) as the derivational principal of discourses, cannot be made paletable (literaly!)
And so the audition fails because language or the "langue" is not sufficiently constructed for what it represents in discursive practice. At the zenith of the teleological project, when temporal conceptualization extinguishes itself from being quantified into being qualified, at the last quarter of the era, perhaps this work will be gleamed from the resevoire and conrgessively discussed.