[Sharp] and heavy were named by way of acoustical metaphor; for when it comes to materials there is both the sharp and the heavy.[1] For the term 'sharp' is used for that which produces action quickly, as in "the knife is sharp," because it pricks quickly, whereas 'dull' is that which produces action slowly, the sort of thing that does not prick but shoves, like the pestle. For when we want to make things suitable for pricking we make them sharp-edged, but for shoving, dull-edged. Likewise in the case of sounds, we use the term 'sharp' for the one that presents itself quickly to the senses and quickly comes to a halt,[2] but the 'heavy' is the counterpart to the dull; it presents itself slowly to the senses and quickly comes to a halt. As with strings that are stretched more, like the lowest[3] gives off tones that are sharper than those that are stretched to a lesser degree, such as the highest. For the lowest, when it is plucked, strikes the air more quickly than the others on account of the tension and makes the tone the sharpest. And it did this in a brief time, but preserved [it] to a great extent.
But the sharp and the dull [exist] in separate types and not in the same category, in voice, in flavor, in a knife.[4]