The two hypotheses, if they may be so styled, are, however, substantially the same, and may be met by the same answer that we are not conscious of the alleged simple or abstract ideas — that there is nothing corresponding to their names in our minds.

The question resolves itself, in fact, into the one considered in my last Letter.

In whatever way the alleged ideas may be said to originate, their names, or the abstract terms so abundant in speech, must bring them to mind, if they actually exist.

Now, my doctrine is, that as we are unable to perceive, so we are unable to conceive any separate entity corresponding to an abstract term: nor are we conscious of any peculiar mental phenomenon to which that term can be applied. In different language, we have no ideas in the mind answering to such words as extension and motion, but, when they are used, we think of an extended and moving body. Our thoughts on such occasions may frequently be vague, shadowy, indistinct, and fugitive, but their real character is what I have described it to be. Try to think clearly and deliberately of extension, and you will find yourself thinking of some extended substance: try to think clearly and deliberately of motion, and you will find yourself thinking of some moving body.

It is somewhat singular that Mr. Stewart (who was a decided nominalist, and considered that com

mon names and other general terms do not denote general ideas; that all which is general in the case, lies in the words) should yet maintain that we have ideas corresponding to such general abstract terms as extension, motion, causation, truth, certainty, and the rest. As a nominalist, he would hold that the common name extended substance does not denote a substance without particular qualities, nor raise up an idea of such a substance, but recalls one or more particular substances formerly perceived through the organs of sense; and yet he considers the general abstract term extension as having a corresponding abstract, or, as he denominates it, simple idea in the mind, or as being the name of such an idea.

He manifestly either was not aware that his "simple ideas" are what others denominate abstract, or did not discern the relation between common names and abstract terms, and that any proposition composed of the latter may be completely expressed in concrete language.

If there are such abstract ideas as he contends for, what becomes of them when their names, as they always may be, are replaced by concrete general terms which fully convey the same meaning, and which he himself maintains, raise up ideas only of particular objects?

The singular attempt of these philosophers to distinguish between what we perceive, and ideas of a non-representative character springing up in the

mind on occasion of perception, was probably owing in part to the habit of regarding the senses as distinct from the mind, and as in themselves unin telligent transmitters to the understanding of information from without, instead of considering the mind just as directly engaged in perceiving objects through the organs of sense as in recollecting, discerning, or reasoning, when the senses are not in activity. They are alike states or modifications of consciousness. Extended substances, figured objects, causes producing effects, bodies moving or resting, are all perceived through these organs; and when they have passed away, or are withdrawn, the mind has or may have ideas of them, but it can have no other ideas relating to material external existences than those which represent such things as have been perceived. Perceiving is the grand original mental operation on which, as far as the material world is concerned, conceiving is altogether dependent, and by which it is rigidly circumscribed. In different language, all our ideas are of a representative character, and cannot be otherwise.

In illustration of the truth that we have no ideas relating to external material things which have not originated in perception, or which are additional to the ideas representing what we have perceived, I venture to assert that there is nothing we can think of regarding external objects, no form into which we can throw our ideas, which we could not

perceive were the objects actually before us: or, in other words, we can have no ideas whatever of external objects, or relating to them, of which the counterparts could not be perceived through the organs of sense, were the objects in presence.

We can, it is true, form in our minds the conception of an object that we have never seen, as is exemplified in the common instance of a golden mountain; but if such an object were set before us, there would be no more difficulty in seeing it than there actually is in conceiving it. The elements out of which the conception was put together— gold and a common mountain were originally perceived through the eye; and in what way soever such elements are combined in imagination, to the eye they would be perceptible, could a corresponding combination of realities be brought before it.

LETTER XXV.

EXAMPLES OF IMPORTANT GENERAL AND ABSTRACT

TERMS.

THE importance of forming a just and clear conception of what passes in the mind when common names and abstract terms are employed, can scarcely be overrated.

It is not going too far to say, that a complete mastery of this part of mental philosophy furnishes a key for most of the difficulties besetting the subject, and throws a powerful light on all speculation whatever. It will be found an invaluable guide through the bewildering mazes of mystical metaphysics. In proof of these assertions, I shall select a few important phrases for examination.

I will draw your attention, in the first place, to the names of those mental phenomena which have occupied so much space in the present series of Letters.

The appellations under which we are accustomed to group the operations and affections of the mind, are nothing but general terms or common denominations. We call one kind of mental action