Notices respecting New Books. 385 
€ A visible line cannot be of any one colour; because it is proved 
{by the ‘first law) that no one colour ever can have a line. If 
then a visible line have any colour, it must be a part of each of 
two contiguous colours: but this would show a double line to 
every object, which we know to be a result utterly contradicted by 
the fact—Moreover, if any such double or two lines be supposed, 
it is plain that each one is but a rim of its own surface; and what 
is surface cannot be line; neither can two contiguous sensations 
of colours appear to us as forming a five, until we > mark the place 
where both colours cease to be, by reason of their coming in con- 
tact. 
** Tt is true that we see instances enough of breadth in what 
are called softened lines, or where two colours blend: but none 
of these are visible lines; thev are all visible surfaces, and they 
must be stript of the appellation of dimes, in an inquiry like the 
present.—Visible lines areall those lines which are void of breadth 
to the naked eye, and which can further attest that they are 
breadthless to the naked eye, by showing no breadth when sub- 
jected toa magnifying power.—Such lines are raised in our sen- 
tient by our looking at the letters of good printing, as divided 
from the white field of the paper; and such, too, aie seen from 
looking at most other objects. 
* It is here an obvious truth, that a visible line which shows 
no breadth under a magnifying power, can have no breadth to the 
naked eye. tis therefore vain to try to overturn the fact, even 
if we could by the strongest power produce any evidence of 
breadth: for it must still remain, that the natural eye of man 
enables him to see no Lines, but lines that are void of breadth in 
his apprehension of ihem. 
‘Finally: But if, in the face of experiment and of common sense, 
any person choose to assert that a visible line has invisible lreadths 
then, (I repeat it-here) this absurd contradiction in terms, if suf+ 
fered to stand for an objection, could be of no concern to the 
laws of vision; for these Jaws must still be axioms, and a visible 
Line must still be nothing but a line of contrast between two sen- 
sations : and the contrast line must still, and for ever, be where 
the sensations are which form it, which is i the mind itself. 
“* Hereupon, (urged by the moment of the evidence, and by the 
infinite magnitude of the consequence,) I make the appeal, in 
this one question,—Will it (against the "four axioms of vision) be 
ever affirmed, that visible Jigures are the distant ihings of an 
external world ? or, Will it be ever affirmed that visible figure 
is not a phenomenon of the mind?—This is an appeal that can 
mot die.” . 
. 
Vol,-50, No, 235, Nov, 1817. Bil 2 eh SLX pe 
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