Page:Ferrier's Works Volume 1 - Institutes of Metaphysic (1875 ed.).djvu/177

RhPROP. V.———— refers us in its exposition of the primary qualities, is this, that we have a distinct and direct knowledge of them as they exist, not in our minds, but in the things which are made known to us through their means. We have a clear apprehension of the objective presence of extension, figure, and solidity, as the properties of external things. In this respect the primary differ from the secondary qualities, of whose objective existence we have no distinct knowledge or conception.

Such is the psychological distinction between the primary and the secondary qualities of matter, and between sensation and perception. Sensation is the faculty which doubtfully and obscurely indicates the objective existence of the secondary qualities; while perception is the faculty which announces dearly and unmistakably the objective existence of the primary. Sensation, it is said, reveals the sentient subject; perception the sensible and objective world.

6. In itself, and under certain limitations, this distinction is harmless. Although the analysis is of no importance, and answers no purpose, there is nothing positively erroneous in the affirmation that the primary qualities of matter are phenomena of a different order from the secondary; that the latter are obscure and sensational; that the former are clear and perceptible. Psychology might, indeed,