LX.
In the Scales of Secondary Qualities, it is a condition (in order that the scale may be complete,) that every example of the quality must either agree with one of the degrees of the Scale, or lie between two contiguous degrees. (iv. 4.)
LXI.
We perceive by means of a medium and by means of impressions on the nerves: but we do not (by our senses) perceive either the medium or the impressions on the nerves. (iv. 1.)
LXII.
The Prerogatives of the Sight are, that by this sense we necessarily and immediately apprehend the position of its objects: and that from visible circumstances, we infer the distance of objects from us, so readily that we seem to perceive and not to infer. (iv. 2.) 17
LXIII.
The Prerogatives of the Hearing are, that by this sense we perceive relations perfectly precise and definite between two notes, namely, Musical Intervals (as an Octave, a Fifth); and that when two notes are perceived together, they are comprehended as distinct, (a Chord,) and as having a certain relation, (Concord or Discord.) (iv. 2.)
LXIV.
The Sight cannot decompose a compound colour into simple colours, or distinguish a compound from a simple colour. The Hearing cannot directly perceive the place, still less the distance, of its objects: we infer these obscurely and vaguely from audible circumstances. (iv. 2.)