The following is quoted from my current correspondence to my friend Mary about these works. It's significant because it is leading me to reconsider the philosphy of art – or, perhaps I should say, to consider the philosophy of art with some seriousness for the first time.
The variety of expressive sounds certainly impresses. As does the brevity, extreme even by Webern's standards. Webern composed only two further pieces in this style, the Op. 10 Orchestral Pieces and the Op. 11 Three Little Pieces for piano and cello. I think he sensed at this point that he could go no further with such a condensed instrumental form and all his subsequent instrumental works were serial compositions of somewhat greater length (although still extremely brief by the standards of most other composers). It was the latter serial pieces that had such a profound influence on the music of the 1950s and 1960s. These were extensively analyzed and discussed. The Bagatelles, in contrast, have undergone very little musical analysis. They provide so little material onto which an analytical theory can be hung, I suspect.
This is what Webern himself wrote about them (in a letter to Alban Berg):
"While working on them I had the feeling that once the 12 notes had run out, the piece was finished. Much later I realized this was all part of the necessary evolution. I wrote down the chromatic scale in my sketchbook and struck out single tones from it. Why? Because I had convinced myself that the tone was already there. It sounds grotesque, incomprehensible, and it was immensely difficult. The ear decided absolutely correctly that the man the man who wrote down the chromatic scale and struck out the notes was not a fool."
An extraordinary statement from a composer – whose stuff, after all, is those very tones. The step from this statement to the silence of John Cage's 4' 33" is not a long one even though Cage's work opened up a whole new aesthetic of sound and music and the relation between the two. Webern's work might be considered the pivot between worlds.
I found a fascinating book – "Is There Truth In Art?" by Herman Rapaport that has this to say about Webern's music – specifically in relation to Webern's own comments quoted above about his Bagatelles.
"What is music, according to Webern, but an art threatened by its own temporality, duration, persistence, or continuence? What is music but something other than the work that we hear, the work as timely utterence? Clearly, Webern's remark about twelve notes being enough suggests that what continues is not really music, but something else that we call the work of art, that something else which is destined to meet its hearer in the concert hall. Yet, Webern knew quite well that without continuance, and a coming-to-the-fore of what is at rest, music does not come into being at all. Indeed, if the truth of the musical work is destined to be conveyed to an auditor by means of someone who performs or brings the work into being in time, the appearance of the work must be defined in Heidegger's terms as a 'gather[ing of] the rising of the coming-to-the-fore' that nevertheless holds fast to the "ever possible absenting into concealedness". To put this another way, Webern asks us to consider that music is not simply a time-based art in the sense of that which needs duration in order to come to the fullness of its being as art. Rather Webern's work suggests that the temporality of music may be the very condition under which there is an ever-possible absenting of art into concealedness. What remains in time, therefore, is the otherwise than authentic being of the work – a being that is inhuman. What remains is the trace of silence, the disappearance of the work which comes to the fore as a work that barely survives performer and listener, but that nevertheless proffers itself as something human, audible, transmittable, temporal, understandable, and truthful – that is to say, as the otherwise-than-silence, the otherwise-than-time. It is here, of course, that Webern approaches a Heideggerian conception of aletheia as the presencing of an essence by means of the coming to pass of a counter-essence.
(Rapaport, pp. 65-66. He is referencing Heidegger's "What Is Called Thinking?")
I quote this not so much to endorse the argument, but more as an example of how Webern's music can stimulate the listener to consider the truth, reality and meaning of music in ways that other composers might not, at least not so distinctly or directly.