The importance of correct powers of Abstraction is seen when we realize that all concepts or general ideas are but combinations of abstract qualities or ideas. As Halleck says: “The difference between an _abstract idea_ and a _concept_ is that a concept may consist of a bundle of abstract ideas. If the class contains more than one common quality, so must the concept; it must contain as many of these abstracted qualities as are common to the class. The concept of the class _whale_ would embody a large number of such qualities.” As Brooks says: “If we could not abstract, we could not _generalize_, for abstraction is a condition of generalization.” The last-mentioned authority also cleverly states the idea as follows: “The products of Abstraction are _abstract ideas_, that is, ideas of qualities in the abstract. Such ideas are called _Abstracts_. Thus my idea of some particular color, or hardness, or softness, is an abstract. Abstract ideas have been wittily called ‘the ghosts of departed qualities.’ They may more appropriately be regarded as the spirits of which the objects from which they are derived are the bodies. In other words, they are, figuratively speaking, ‘the disembodied spirits of material things.'”
The cultivation of the faculty of Abstraction depends very materially, in the first place, upon the exercise of Attention and Perception. Mill holds that Abstraction is primarily a result of Attention. Others hold that it is merely the mental process by which the attention is directed exclusively to the consideration of one of several qualities, properties, attributes, parts, etc. Hamilton says: “Attention and Abstraction then are only the same process viewed in different relations. They are, as it were, the positive and negative poles of the same act.” The cultivation of Attention is really a part of the process of the cultivation of the faculty of Abstraction. Unless the Attention be directed toward the object and its qualities we will be unable to perceive, set aside, and separately consider the abstract quality contained within it. In this process, as indeed in all other mental processes, Attention is a prerequisite. Therefore, here, as in many other places, we say to you: “Begin by cultivating Attention.”
Moreover, the cultivation of the faculty of Abstraction depends materially upon the cultivation of Perception. Not only must we _sense_ the existence of the various qualities in an object, but we must also _perceive_ them in consciousness, just as we perceive the object itself. In fact, the perception of the object is merely a perception of its various qualities, attributes and properties, for the object itself is merely a composite of these abstract things, at least so far as its perception in consciousness is concerned. Try to think of _a horse_, without considering its qualities, attributes and properties, and the result is merely _an abstract horse_–something which belongs to the realm of unreality. Try to think of _a rose_ without considering its color, odor, shape, size, response to touch, etc., and you have simply _an ideal rose_ which when analyzed is seen to be a _nothing_. Take away the qualities, properties and attributes of anything, and you have left _merely a name_, or else a transcendental, idealistic, something apart from our world of sense knowledge. Thus it follows that in order to _know_ the qualities of a thing in order to classify it, or to form a general idea of it, we _must_ use the Perception in order to interpret or translate the sense-impressions we have received regarding them. Consequently the greater our power of Perception the greater must be the possibility of our power of Abstraction.
Beyond the cultivation, use and exercise of the Attention and the Perception, there are but few practical methods for cultivating the faculty of Abstraction. Of course, _exercise_ of the faculty will develop it; and _the furnishing of material for its activities_ will give it the “nourishment” of which we have spoken elsewhere. Practice in distinguishing the various qualities, attributes and properties of objects will give a valuable training to the faculty.
Let the student take any object and endeavor to analyze it into its abstract qualities, etc. Let him try to discover qualities hidden from first sight. Let him make a list of these qualities, and write them down; then try to add to the list. Two or more students engaging in a friendly rivalry will stimulate the efforts of each other. In children the exercise may be treated as a game. _Analysis of objects into their component qualities, attributes and qualities–the effort to extract as many adjectives applicable to the object_–this is the first step. The second step consists in _transforming these adjectives into their corresponding nouns_. As for instance, in a rose we perceive the _qualities_ which we call “redness,” “fragrance,” etc. We speak of the rose as being “red” or “fragrant”–then we think of “redness,” or “fragrance” as abstract qualities, or things, which we express as nouns. Exercise and practice along these lines will tend to cultivate the faculty of Abstraction. By knowing qualities, we know the things possessing them.