Philosophy Blog
A ratio is a relation between two numbers. It is not a physical object but an abstract one.
Our senses of hearing and sight are able to apprehend the ratio between two sense impressions. When we hear an octave sung or sounded, we experience a distinct pleasure. Our ears are a measuring instrument but do not flash numbers on a screen for us.
Instruments which do so, tell us that in an octave the number of vibrations per second of the lower sound is half that of the higher. A simple ratio of vibrations such as 1 : 2 is pleasant to the ear whereas complicated ratios sound discordant. To a certain level of accuracy, the eye is also able to detect ratios and see that that one length is, say, twice the length of another.
Our other senses can tell us of ‘more or less’ of the qualities they detect.