ceases to be the same. Let the roughness of the bark and the angles of
the boughs be smoothed or diminished, and the oak ceases to be an oak;
but let it retain its inward structure and outward form, and though its
leaves grew white, or pink, or blue, or tri-color, it would be a white
oak, or a pink oak, or a republican oak, but an oak still. Again, color
is hardly ever even a _possible_ distinction between two objects of the
same species. Two trees, of the same kind, at the same season, and of
the same age, are of absolutely the same color; but they are not of the
same form, nor anything like it. There can be no difference in the color
of two pieces of rock broken from the same place; but it is impossible
they should be of the same form. So that form is not only the chief
characteristic of species, but the only characteristic of individuals of
a species.

Sec. 5. And different in association from what it is alone.

Again, a color, in association with other colors, is different from the
same color seen by itself. It has a distinct and peculiar power upon the
retina dependent on its association. Consequently, the color of any
object is not more dependent upon the nature of the object itself, and
the eye beholding it, than on the color of the objects near it; in this
respect also, therefore, it is no characteristic.

Sec. 6. It is not certain whether any two people see the same color in
things.

And so great is the uncertainty with respect to those qualities or
powers which depend as much on the nature of the object suffering as of
the object acting, that it is totally impossible to prove that one man
sees in the same thing the same color that another does though he may
use the same name for it. One man may see yellow where another sees
blue, but as the effect is constant, they agree in the term to be used
for it, and both call it blue, or both yellow, having yet totally
different ideas attached to the term. And yet neither can be said to see
falsely, because the color is not in the thing, but in the thing and
them together. But if they see forms differently, one must see falsely,
because the form is positive in the object. My friend may see boars blue
for anything I know, but it is impossible he should see them with paws
instead of hoofs, unless his eyes or brain are diseased. (Compare Locke,
Book ii. chap. xxxii. Sec. 15.) But I do not speak of this uncertainty as
capable of having any effect on art, beca