Book 1, Chapter 3, Footnote #04
Primary qualities also known only thru sensation
An attempt, indeed, has been made by Reid and others, to establish that although some of the properties we ascribe to objects exist only in our sensations, others exist in the things themselves, being such as cannot possibly be copies of any impression upon the senses; and they ask, from what sensations our notions of extension and figure have been derived? The gauntlet thrown down by Reid was taken up by Brown, who, applying greater powers of analysis than had previously been applied to the notions of extension and figure pointed out that the sensations from which those notions are derived, are sensation of touch combined with sensations of a class previously too little adverted to by metaphysicians, those which have their seat in our muscular frame. His analysis, which was adopted and followed up by James Mill, has been further and greatly improved upon in Professor Bain's profound work, The Senses and the Intellect, and in the chapters on ``Perception'' of a work of eminent analytic power, Mr. Herbert Spencer's Principles of Psychology.
On this point M. Cousin may again be cited in favour of the better doctrine. M. Cousin recognises, in opposition to Reid, the essential subjectivity of our conceptions of what are called the primary qualities of matter, as extension, solidity, &c., equally with those of colour, heat, and the remainder of the so-called secondary qualities.---Cours, ut supra, 9me lecon.