From: W. Ong, Orality and Literacy.

Sight isolates, sound incorporates. Whereas sight situates the observer outside what he views, at a distance, sound pours into the hearer. Vision dissects, as Merleau-Ponty has observed (1961). Vision comes to a human being from one direction at a time: to look at a room or a landscape, I must move my eyes around from one part to another. When I hear, however, I gather sound simultaneously from every direction at once: I am at the center of my auditory world, which envelopes me, establishing me at a kind of core of sensation and existence. This centering effect of sound is what high-fidelity sound reproduction exploits with intense sophistication.

You can immerse yourself in hearing, in sound. There is no way to immerse yourself similarly in sight. By contrast with vision, the dissecting sense, sound is thus a unifying sense. A typical visual ideal is clarity and distinctness, a taking apart (Descartes’ campaigning for clarity and distinctness registered an intensification of vision in the human sensorium— Ong 1967b, pp. 63, 221). The auditory ideal, by contrast, is harmony, a putting together. Interiority and harmony are characteristics of human consciousness.

The consciousness of each human person is totally interiorized, known to the person from the inside and inaccessible to any other person directly from the inside. Everyone who says ‘I’ means something different by it from what every other person means. What is ‘I’ to me is only ‘you’ to you. And this ‘I’ incorporates experience into itself by ‘getting it all together’. Knowledge is ultimately not a fractioning but a unifying phenomenon, a striving for harmony. Without harmony, an interior condition, the psyche is in bad health.