^35 
on Logic uTid Metaphysics. 
1812.] 
Vses of this sense—morjs exquisite 
and perfect in man than jn any other 
animal.^ 
V. Qf the Sense of Sight.-^Anatomi¬ 
cal structure of the organ of vision.«»?« 
Original and acquired perceptions of 
sight.—Physiology or l?iws of vision.— 
The eye a dioptrical instrument.—Means 
by which we estimate the distance and 
magnitude, and thus acquire a correct 
knowledge ofexternal objects—fl,Greater 
or less portion of the Retina on which 
the rays of light fall.—i!>, Muscular action 
of the ball of the eye, affecting the con- 
vexty of the cornea^ or the pellucid ex¬ 
ternal segment of the globe of the eye, 
and likewise shortening or lengthening 
the axis of vision.—c. Previous knowledge 
of the magnitude and distance of conti¬ 
guous or intervening objects.—Single 
and double, or depraved vision. When 
the rays of light fail on corresponding 
points of both Retince, vision single or 
natural—when they fall on discordant 
points, vision double or depra'ed— 
Images of external objects printed on 
the Retina’^ in inverted positions—pro¬ 
cess of judging concerning the true posi¬ 
tion of objects inexplicable by any known 
law of vision—To be referred to habits 
early and insensibly acquired, like the 
perception of the distance and magni¬ 
tude of objects.—Squinting explained—^ 
Remedies proposed.—Light.—Analysis of 
light.—Existence of the material world. 
—Proofs of the existence of the universe 
brought forward hy Dr. Reid.— Diffi¬ 
cult, in fact, to prove the existence of 
external arguments.—Unnecessary to ad¬ 
duce any such proof.—Impossible to call 
the reality of external objects in ques¬ 
tion—Belief of them intuitive, and re¬ 
ferable to an ultimate law of the human 
mind—This belief immediate, universal, 
and irresistible — Assumed as a Posfnlaie 
in all our reasoning concerning external 
perception—Admitted by sceptists them¬ 
selves, at the very moment they argue 
against it.—The very reasonings and ar¬ 
guments of those sceptists who deny the 
existence of material iibjects, pre-suppose 
the existence of those to whom these 
reasonings and arguments are addressed. 
5. Of Attention. 
* ^‘Ex sensibus ante ciEtera homini 
tactus, cein gustatus; reliquis superatur muf¬ 
tis, Aquilas clarius cernunt, vultures sa- 
gacius odorantur j liquiJius audiunc talpa?, 
obrutae terra, tarn dense atque surdo Naturae 
eieme.nto.”—C. Fuml Hist. Natur. Lib. x. 
cap. U2a 
6 . Of Conception; or that faculty of 
the mind by which it can recollect those 
sensations of which it was formerly con¬ 
scious, and review external objects for* 
merly perceived. 
T. Of Abstract ion. —Under this head 
the following topics will, according to my 
judgment, offer themselves to our consi¬ 
deration:—The origin of our ideas— 
Precise import of that term.— Idea un¬ 
derstood, whenever it is mentioned ia 
this Course, as synonimous with thought^ 
or notion, or appi^ehension. —Theory of 
]\Ir. Locke concerning the origin of our 
ideas; viz. that all our ideas are derived 
from sensation and reflection—This 
theory imperfect, and will not account 
for the origin of all our ideas—Because 
many of our ideas are not derived either 
from sensation or reflection—Such are 
our ideas of Time, of Motiofi, of Personal 
or Mental Identity, and many others. — 
The only account which can be given 
of the origin of these ideas is, that they 
spontaneously arise in the mind during 
tiie exercise of those faculties wliich are 
subservient to their generation —Repu¬ 
tation ol Locke’s doctrine of Innate 
Ideas — Sei'ise ia which ideas may be said 
to be innate. —Abstract ideas. — Use and 
abuse of words, as signs of our ideas.— 
Degerando. Dc la Generation des Con^ 
noissances Humaines. — Doctrines of the 
Nomina/isis. —Of the Realists. —Of the 
Concephialists. Bruckerii Hist. Philo- 
soph. Critica, admirably abridged and 
translated into English by Dr. Enfieid. 
S. Of Memory 
9. Of Imagination. 
10. Of the Association of Ideas.— ^ 
Sleep. — Phenomena of dreaming. 
Of Judgment. — In this part of t’he 
Coarse, the fumJaiuental principles oa 
which our judgment rests, that is, the 
different kinds of evidence, will naturally 
claim our attention. 
Evidence is usually divided into, 
i. Instinctive evidence, and 
11. Deductive evidence. BotJr these 
kinds of evidence, and the subdivisions of 
w'hich they admit, will receive copious 
illustration in the proper place. 
In investigating the nature of judg¬ 
ment the various kinds of propositions 
will come to be considered. 
Having thus examined the nature of 
judgment, the various kinds of evidence, 
and the nature of propositions, I shall 
propose certain rules wliich may assist 
the student in forming his judgment con¬ 
cerning the various subjects tliat may re¬ 
quire the exeitioa of this faculty. Here 
