Abstraction is that faculty of the mind by which we abstract or "draw off," and then consider apart, the particular qualities, properties, or attributes of an object, and thus are able to consider _them_ as "things" or objects of thought. In order to form _concepts_ or general ideas, from our _percepts_ or particular ideas, we must consider and examine two common points or qualities which go to make up _differences and resemblances_. The special examination or consideration of these common points or qualities result in the exercise of Abstraction. In the process of Abstraction we mentally "draw away" a quality of an object and then consider it as a distinct object of thought. Thus in considering a flower we may _abstract_ its qualities of fragrance, color, shape, etc., and think of these as things independent of the flower itself from which they were derived. We think of _redness_, _fragrance_, etc., not only in connection with the particular flower but as _general qualities_. Thus the qualities of redness, sweetness, hardness, softness, etc., lead us to the abstract terms, _red_, _sweet_, _hard_, _soft_, _etc._ In the same way courage, cowardice, virtue, vice, love, hate, etc., are abstract terms. No one ever saw one of these things--they are known only in connection with objects, or else as "abstract terms" in the processes of Thought. They may be known as qualities, and expressed as predicates; or they may be considered as abstract things and expressed as nouns. In the general process of Abstraction we first draw off and set aside all the qualities which are _not common_ to the general class under consideration, for the concept or general idea must comprise only the qualities common to its class. Thus in the case of the general idea of horse, size and color must be abstracted as non-essentials, for horses are of various colors and sizes. But on the other hand, there are certain qualities which _are common to all horses_, and these must be abstracted and used in making up the concept or general idea.