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 ...

42:EXTERNAL PERCEPTION.
this view of the subject, it follows, that it is the external objects
themselves, and not any species or images of these objects, that
Thus, I perceive a tree; there is here an object which is perceived, and an
act of the mind by which it is perceived; and the two are not only distinguishable, but are extremely unlike in their natures. And the tree'exists,
whether it is perceived or not. The tree, also, which is the object perceived, is made up of a trunk, branches, and leaves; the act of the mind
by which it is perceived has neither trunk, branches, nor leaves.
Every perception is accompanied by a sensation, without which it could
not exist. But every sensation has not a perception as its necessary concomitant; it may exist alone. When I smell a rose, there is in this operation both sensation and perception. The agreeable odor I feel, considered by itself, without relation to any external object, is merely a sensation.
This sensation may be felt, when no rose is perceived; as when I enter a
room strongly impregnated with otto of rose, though the flower - the rose
itself- is not there. This sensation can be nothing else than it is felt to
be; its very essence consists in being felt, and when it is not felt, it is
not.
Now let us attend to the perception which we have in smelling a rose.
Perception always has an external object; and the object of my perception, in this case, is that quality in the rose which I discern by or through
the sense of smell. This quality in the rose, which produces an effect on
my olfactory nerves, is the object of perception; and the act by which I
recognize it, and believe it to exist, is perception.
Sir WV. Hamilton even lays it down as a general rule, that, above a certain point, the stronger tle Sensation, the weaker the Perception; and the distincter the Perception, the less obtrusive the Sensation. In c fher words, Pereeption and Sensation are alwzays found in an inverse ratio to each other. Thus,
if I strike my hand lightly against the corner of the table, the sensation
which is produced is slight, and I have a very distinct perception of the
hardness and angularity of the table which produce the sensation. But if
I strike my hand violently against it, the sensation produced is acute and
painful, andt, my attention being absorbed by it, I hardly perceive the shape
of the object which has done me the injury. So, again, if I look at the
unclouded sun at mid-day, the sensation produced is so vivid and overpowering, that I have hardly any perception either of its form or color. But
if I look at the same object towards evening, when it is partially obscured
by clouds, the sensation is light. and agreeable, and I have a very distinct
perception of the sun's circular form and red or golden color.
Buet observe, the sensation which is felt, and the quality which is perceived, are both called by the same name. In the instance first given, the
smell of a rose is the name given to both. Hence has arisen the curious
question, whether the smell be in the rose, or in the mind that feels