Among the earlier articles here, that concerning composing without text is one of the most far-flung and rambling. Especially as the topic recurs, it becomes necessary to elaborate some of the issues developed therein more coherently. There are two fundamental notions acting as poles for such a discussion. On one side is the basic fact that speech and the voice are the primary basis of human communication, and consequently the most nuanced "instruments" for musical expression. On the other side is the idea of untexted music as "universal language" and with it the greater musical complexity allowed by not restricting melodic expression to real phonemes. The two mingle frequently as instruments quote melodies with text, or even as the voice mimics instrumental articulation styles.
The song is one of the most fundamental forms of musical expression. It is central to most musical cultures, although not to all. Western musical history can be viewed as a series of events deemphasizing the song per se in favor of grander formats and elaborations. Nonetheless, the song has retained much of its vitality, especially as it continues to act as material for larger forms. It is of course ubiquitous in popular music as well. Cultures with percussion-oriented music are about the only places where one cannot trace a similar outline, and of course in many cultures the song is still very much paramount for art music. Even in Western art music, the song has its up and down periods; sometimes it regains some centrality, whereas the current trough can probably be related to a reaction against the increased economic power of popular music as a form of expression.
The latter has yielded an implication that music without words is more sophisticated. In its most tangible sense, the sophistication exists in the fact that different listeners can more readily inject different personal meanings into a piece without an explicit text. The notion of "universal language" arises from conclusions regarding whether superficially different hearings of a piece may be fundamentally the same. Perhaps. However, as noted in the earlier article, the history of Western instrumental music was clearly subordinated to that of vocal music until at least modern times. As instrumental music developed an independent existence, it was a reflection of vocal forms and even material. It was with the classical period, and especially with Beethoven, a composer with little use for singers yet with a startling pianistic eloquence, that supporters of instrumental music could actually make some claims to preeminence. Even then, opera and song forms were central genres for most 19th century composers.
If issues such as religious disputes encouraged composers to make their music less explicit, less controversial, and ultimately less text-oriented, instrumental accompaniment was also a natural and purely musical development. Besides the natural, yet controversial, idea of letting instruments handle some lines of polyphony, there was real instrumental accompaniment subordinate to the voice. The vocal recitative with harmonic accompaniment and instrumental interludes had to wait for the late 16th century to emerge as a leading format, although its potential seems so obvious today. Yet, before that, it is clear that functional music frequently used accompaniment for reasons such as keeping time; this was especially necessary for dancing, and so together with mimicking the vocal repertory, dance is one of the primary founts of instrumental music. The same is true in another culture such as Bali, which emphasizes instrumental forms among its art music; it also emphasizes dance as highest among its arts.
Dancing is a concrete physical thing, less abstract than poetry, if we are to make such a comparison. Yet, somehow this fusion between dance music and poetic accompaniment led to purely instrumental music almost universally being hailed as the most abstract of Western artistic outputs. This two-headed basis was a clear spur toward dialectic ideas (primarily dualist, of course) and with them the sonata form. The abstraction seemingly implied by dissociating music-making from textual or semantic elements was relatively slow to develop in practice, especially as concepts of melody revolved around vocal phrasing. Only with the postmodern styles was it possible to divorce melodic ideas, or form in their absence, from sung melody and go on to create truly non-textual "instrumentalistic" music.
The implications of real non-semantic music, let alone the public's willingness to embrace it, are anything but decided. The inherent abstraction has been, in some ways, a return to the "music as science" idea of the medieval era. At that time, even with a text, music was as abstract as it could be, at least according to the constraints of the time. Despite the general lack of specifically instrumental music from the medieval era, this connection is made tangibly by the not infrequent instrumental interpretations included on record, and especially by the growing number associated with the Ars Subtilior repertory. Even though phrasing and melodic emphasis is clearly text-oriented, the contrapuntal & rhythmic implications of the music serve to evoke a more instrumental conception, perhaps based on our own modern biases. Various techniques seem equally suited to different transcriptions.
The future of textless music, and with it the reevaluation of previous textless music, is consequently tied in some way to the future of medieval music. Although the possibilities of textless music have afforded a ready outlet for abstract music in the face of newly imposed text-oriented restrictions, the ultimate possibilities of composition in this arena are simply too vast to circumscribe. Especially with the advent of the computer and its arbitrary sound combinations, both composers and the public are presented with such a myriad of possibilities that the entire experience has been disorienting, lacking as it does the human orientation of text. In short, abstract music is no longer confined to accompanying other things, and consequently it is difficult to find oneself in it. Fundamentally, it can be sophisticated only after that happens.