tion; and in our wisdom we give it a name; we call it motion by impulse. But can any man tell what motion is? Still more can he point out, how motion passes from one body to another, when the particles of those bodies come in contact, if indeed there can be any actual contact?—Such are the doubts, that press upon us, wherever we turn our eyes. But this is not said to discourage inquiry. The first step in laying a good and broad foundation is to be fully sensible of our ignorance, and of the mind's limits.

CHAPTER TWELFTH.

ABSTRACTION.

§. 133. Abstraction implied in the analysis of complex ideas.

The remarks, which have been made, in the course of the foregoing chapter, on the analysis and examination of our Complex Intellectual states, naturally lead to the consideration of another subject in some respects intimately connected with that topic. When we have once formed a complex notion, (no matter at what period, in what way, or of what kind,) it not unfrequently happens that we desire, for various reasons, to examine more particularly some of its parts. Very frequently this is absolutely necessary to the full understanding of it. Although undoubtedly its elementary parts once came under review, that time is now long past; it has become important to institute a new inspection, to take each simple notion involved in it, and examine it by itself. And this is done by means of the process of ABSTRACTION, and in no other way.

By the aid of that process, our complex notions, however comprehensive they may be, are susceptible, if one may be allowed so to speak, of being taken to pieces, and the elementary parts may be abstracted or separated from each other; that is, they are made subjects of consideration apart

from other ideas, with which they are ordinarily found to be associated. And hence, whenever this is the case in respect to the states of the mind, they are sometimes called ABSTRACTIONS, and still more frequently are known by the name of

ABSTRACT IDEAS.

For the purpose of distinctness in what we have to say, they may be divided into the two classes of Particular and General; that is to say, in some cases the abstraction relates only to a single idea or element, in others it includes more. -General Abstract Ideas, (or the notions which we form of Genera and Species,) will form a distinct subject of consideration.

§. 134. Instances of particular abstract ideas.

We shall proceed, therefore, to remark here on Particular abstractions. Of this class the notions, which we form of the different kinds of colors, may be regarded as instances. For example we hold in our hand a rose; it has extension, color, form, fragrance. The mind is so deeply occupied with the color, as almost wholly to neglect the other qualities. This is a species of abstraction, although perhaps an imperfect one, because, when an object is before us, it is difficult, in our most attentive consideration of any particular quality or property, to withdraw the mind wholly from the others. When, on the contrary, any absent object of perception occurs to us, when we think of or form a conception of it, our thoughts will readily fix upon the color of such object, and make that the subject of consideration, without particularly regarding its other qualities, such as weight, hardness, taste, form, &c. We may also distinguish in any body, (either when present or still more perfectly when absent,) its solidity from its extension, or we may direct our attention to its weight, or its length, or breadth, or thickness, and make any one of these a distinct object in our thoughts.

And hence, as it is a well known fact, that the properties of any body may be separated in the view and examination of the mind, however closely they may be connected in their appropriate subjects, we may lay down this statement in respect to the states of the mind before us; viz. When any quality or attribute of an object, which does not exist by itself, but in a state of combination, is detached by our minds

from its customary associates, and is considered separately, the notion we form of it becomes a particular abstract idea. -The distinctive mark of this class is, that the abstraction is limited to one quality. It should perhaps be particularly added, that the abstraction or separation may exist mentally, when it cannot take place in the object itself. For instance, the size, the figure, length, breadth, color, &c. of a building may each of them be made subjects of separate mental consideration, although there can be no real or actual separation of these things in the building itself. If there be any one of these properties, there must necessarily be all.

§. 135. Mental process in separating and abstracting them.

The manner of expressing ourselves on the subject of our abstract notions, to which we have been accustomed, is apt to create and cherish a belief in the existence of a separate mental faculty, adapted solely to this particular purpose. But the doctrine of a power or faculty of abstraction, which is exclusive of other mental susceptibilities, and is employed solely for this purpose, does not appear to be well founded. It will convey an impression nearer the truth to speak of the PROCESS, rather than the power of abstraction. The following statement will be sufficient to show, how those of the first class, or particular abstract ideas are formed.

Although our earliest notions, whether they arise from the senses or are of an internal origin, are simple, existing in an independent and separate state, yet those simple thoughts are very soon found to unite together with a considerable degree of permanency, and out of them are formed complex states of mind. Many are in this way combined together in one, and the question is, how this combination is to be loosened, and the elementary parts are to be extracted from their present complexity?

In answer it may be said, that, in every case of separating a particular abstract idea, there must necessarily be a determination, a choice, an act of the will. This voluntary state of mind must concern the previous complex mental state, when viewed in one respect, rather than another; or what is the same thing, it will concern one part of the com

plex idea rather than another. So that we may truly and justly be said to have not only a desire, but a determination to consider or examine some part of the complex idea more particularly than the others. When the mind is in this manner directed to any particular part of a complex notion, we find it to be the fact, that the principle of association, or whatever principle it is, which keeps the other parts in their state of union with it, ceases, in a greater or less degree, to operate and to maintain that union; the other parts rapidly fall off and disappear, and the particular quality, towards which the mind is especially directed, remains the sole subject of consideration. That is to say, it is abstracted, or becomes an abstract idea. If for example we have in mind the complex notion of any object, a house, tree, plant, flower, and the like, but have a desire and determination to make the color, which forms a part of this complex notion, a particular subject of attention, the consequence is, that, while the quality of color occupies our chief regard, the other qualities will disappear, and no more be thought of. If we determine to examine the weight or extension of an object, the result will be the same; in other words, the extension, weight, color, &c. becoming distinct and exclusive objects of attention, will be abstracted.

This, in the formation of particular abstract ideas, seems to be the process of the mind, and nothing more; viz. The direction of an act of the will to a particular part of a complex notion, and the consequent detention of the part, towards which the mental choice is directed, and the natural and necessary disappearance, under such circumstances, of the other parts.

§. 136. Of generalizations of particular abstract mental states.

The terms GENERALIZING and GENERALIZATION are often found applied to the states of mind under consideration. When we have made any quality of a body a distinct and separate subject of attention, we may further regard it as belonging to one or more objects, according as we find such to be the fact, or otherwise. What is chiefly meant, therefore, when we speak of the generalizing of this class of abstract

notions, is that, in our experience of things, we observe them to be common to many subjects. We find whiteness to be a quality of snow, of chalk, of milk, and of other bodies; and whenever with the simple abstract notion of whiteness we connect in our thoughts the additional circumstance of its not being limited to one body but the property of many, the term may be said to be generalized. And this seems to be all, that can be properly understood by generalization, when applied to the states of mind now before us.

§. 137. Of the importance and uses of abstraction.

The power of Abstraction, as it has sometimes been called, is by no means an unimportant one, even when limited to the separation of the particular or simple elements of thought.

"A carpenter, (says Kames,* speaking of the great utility of abstraction,) considers a log of wood with regard to hardness, firmness, color, and texture; a philosopher, neglecting these properties, makes the log undergo a chemical analysis, and examines its taste, its smell, and component principles; the geometrician confines his reasoning to the figure, the length, breadth, and thickness; in general, every artist, abstracting from all other properties, confines his observations to those, which have a more immediate connection with his profession.

Besides its well-known uses in the various forms of reasoning, (particularly demonstrative reasoning,) abstraction is greatly subservient to the exertions of a creative imagination, as they appear in painting, architecture, poetry, and the other fine or liberal arts. The poet and the painter are supplied with their materials from experience; without having received ideas from some source, they never could have practised their art. But if they do not restrict themselves to mere imitation, they must combine and modify the ideas which they have, so as to be able to form new creations of their own. But every such exertion of their powers presupposes the exercise of abstraction in decomposing and separating actual conceptions, and in forming them anew. The power of abstraction, therefore, may justly be considered as a characteristic of the great masters in the liberal arts. From how many

• Elements of Criticism, Vol III. Appendix.