Elements of the philosophy of the human mind. By Dugald Stewart. Rev. and abridged, with critical and explanatory notes, for the use of colleges and schools. By Francis Bowen ...

EXTERNAL PERCEPTION. 41
aside all the common hypothetical language concerning perception, and to exhibit the. difficulty in all its magnitude, by a plain
statement of the fact.
Statement of Dr. Reid's doctrine. - To what then, it may be
asked, does this statement amount? Mierely to this; that the
mind is so formed, that certain impressions produced on our organs of sense by external objects, are followed by correspondent
sensations; and that these sensations, (twhich have no more resemblance to the qualities of matter, than the words of a language
have to the things they denote,) are followed by a perception of
the existence and qualities of the bodies by which the imrpressions are made: that all the steps of this process are equally
incomprehensible; and that, for any thing we can prove to the
contrary, the connection between the sensation and the perception, as well as that between the impression and the sensation,
may be both arbitrary; that it is therefore by no means impossible, that our sensations may be merely the occasions on which
the correspondent perceptions are excited; and that, at any
rate, the consideration of these sensations, which are attributes
of mind, can throw no light on the manner in which we acquire
our knowledge of the existence and qualities of body.* From
X [The distinction between sensation and perception is the most original
and important feature of Dr. Reid's philosophy. The following explanation of it is nearly in his own words, though it is formed by bringing
together many sentences from different portions of his Inquiry and his
Essays.
The same mode of expression is used to denote sensation and perception;
the things coalesce in our imagination, and are considered as one simple
operation, for the ordinary purposes of life do not require them to be distinguished. But the philosopher needs to distinguish them, and is able to
analyze the operation compounded of them. Thus, - Ifeel a pain; Isee
a tree. The first of these propositions denotes a sensation, the last a perception.'Sensation has no object distinct from itself When I am pained, I cannot
say that the pain I feel is one thing, and my feeling it is another thing. They
are one and the same thing, and cannot be disjoined even in imagination.
The sensation, moreover, can have no existence but in a sentient mind;
pain, when it is not felt, has no existence.
Perception, on the other hand, always has an object distinct firom itself
4*