Here are two definitions as totally distinct as any two can be; and he that sees not in them a difference of _substance_, sees it nowhere: to him all natures are one; and that one, an absurd supposition.
15.

In favour of what is urged by the phrenologists, it may perhaps be admitted, as a natural law, that, "If a picture of a visible object be formed upon the retina, and the impression be communicated, by the nerves, to the brain, the _result_ will be an act of perception."-- _Wayland's Moral Science_, p.4.But it does not follow, nor did the writer of this sentence believe, that perception is a mere act or attribute of the organized matter of the brain.

A material object can only occasion in our sensible organs a corporeal motion, which has not in it the nature of thought or perception; and upon what principle of causation, shall a man believe, in respect to vision, that the thing which he sees, is more properly the cause of the idea conceived of it, than is the light by which he beholds it, or the mind in which that idea is formed?
Lord Kames avers, that, "Colour, which appears to the eye as spread upon a substance, has no existence but in the mind of the spectator."-- _Elements of Criticism_, i, 178.

And Cicero placed the perception, not only of colour, but of taste, of sound, of smell, and of touch, in the mind, rather than in the senses.

"Illud est album, hoc dulce, canorum illud, hoc bene olens, hoc asperum: animo jam haec tenemus comprehensa, non sensibus."-- _Ciceronis Acad._ Lib.