Knowledge by acquaintance is the direct apprehension of something through the senses-- the primary way of knowing. But discursive knowledge includes all that language does... discourse is as important as acquaintance, even if it isn't primary-- the character "Dent Ios" in THE MEMORY OF WHITENESS.Perhaps because Robinson's characters exist in an era far removed from the twentieth century, they don't discuss in detail the archaic origin of their philosophical ideas. Indeed, Robinson has a little bit of fun with the idea of attribution, implying that over time scholars may simply get things wrong, as when one character calls modern literary critic Harold Bloom an "alchemist." However, Dent Ios's dual forms of knowledge may have been borrowed from a similar dualism propounded by Bertrand Russell in 1910: "knowledge by acquaintance and knowledge by description." That said, Russell's duality seems to have been preceded, according to this Wikipedia entry, by similar formulations by at least three other philosophers: John Grote, Hermann von Helmholtz, and William James. I have no idea what if any indebtedness Russell might have to these predecessors, but James apparently reproduces Grote's categories exactly in James's 1890 book THE PRINCIPLES OF PSYCHOLOGY:
There are two kinds of knowledge broadly and practically distinguishable: we may call them respectively knowledge of acquaintance and knowledge-about.
Now, most of these philosophers seem to be talking about how humans organize knowledge according to what James calls "perceptual" and "conceptual" knowledge. The characters of MEMORY, however, are not concerned with the way language encodes perceptions, but with the way that music, the least "linguistic" of the arts, does so. On the next page following Dent Ios's assertion, he adds that, "Music is a dynamic, polyphonic process, while writing is linear and static." This seems like an odd thing to say right after he's claimed that discursive knowledge is as important as that of acquaintance. The second statement seems to privilege the dynamism of the direct sense-experience, and to downgrade the "static" qualities of what Grote and James call "knowledge-about." In the 1941 book PHILOSOPHY IN A NEW KEY, Susanne Langer categorically downgrades music as against the more "assertive" arts:
"[Music] is a limited idiom, like an artificial language, only even less successful; for music at its highest, though clearly a symbolic form, is an unconsummated symbol. Articulation is its life, but not assertion; expressiveness, not expression. The actual function of meaning, which calls for permanent contents, is not fulfilled; for the assignment of one rather than another possible meaning to each form is never explicitly made."-- Susanne Langer, PHILOSOPHY IN A NEW KEY, p. 240.
I would tend to agree with Langer more than with Robinson's characters. For me, although I agree that discursive knowledge is *primarily* linear, I don't think it is necessarily "static." Great philosophers-- and critics-- always combine the linear/horizontal logic of the discursive process with what I have called "vertical meaning." Such meaning is put forth roughly along the same lines that Levi-Strauss imagines myths being a combination of "harmonic" and "melodic" elements. Plato's TIMAEUS, in seeking to describe the perfect society already envisaged in THE REPUBLIC, does not depend purely on linear logic but finesses that logic with a mythic image from outside the immediate argument: the image of the city Atlantis, whose extinction signals a counter-example to the "perfect society" once represented by its contemporary opponent Athens.