478 Dr Antson on Single and Correct Vision, by means of 
part of that image must be referred to the upper part of the ex- 
ternal object corresponding to it, and vice versd ; and again. 
images formed on corresponding parts of the two retinz, and 
referred, according to this law, to external space, must appear to 
come from the same points, 7. e. to represent the same object. 
But here the question immediately presents itself, How is this 
law of Visible Direction originally formed in, or impressed upon, 
the mind? If it be thought to be acquired by experience and 
association, the observations already made apply to, and I think 
set aside that supposition. If it be thought to be independent of 
experience, it implies, in the first place, that the mind has an ori- 
ginal perception of distance by the eye, 7.e. that it is originally 
aware of impressions on the retina being produced by causes at 
a distance from the body, although it draws no such inference 
from impressions on the skin ; whereas not only Brrxe.ry and his 
followers, but Rerp, and most other authors on this subject, have 
believed that it is only by experience that we learn that visible 
objects do not touch the eye ; and this has been generally thought 
to be supported by observations on persons to whom the sense 
of sight has been given suddenly, and at a mature age, by couch- 
ing. 
But farther, this doctrine implies that the mind naturally 
draws an inference, not only as to the position of any impression 
that may be made on the retina, but as to the direction in which the 
ray of light came, that made that impression ; and as that direction 
is not a direct object of sense, and as I apprehend that no reason 
can be given, why a ray should be supposed to have come in the 
direction of a perpendicular to the surface of the retina, rather 
than of any other line falling on that surface,—this theory really 
ascribes our perception of the true number and position of ob- 
jects by the eye merely to the principle of Intuition, i. e. it merely 
states the fact, that the images formed on the retina are referred 
to places in the external world according to this law ; and if we 
regard the theory as a sufficient explanation, we must regard this 
as an ultimate fact in our mental constitution. 
