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termed a genus. That quality which distinguisheth one genus, one species, or even one individual, from another, is termed a modification : thus the same particular that is termed a property or quality when considered as belonging to an individual, or a class of individuals, is termed a modification when considered as distinguishing the individual or the class from another : a black skin and soft curled hair, are properties of a negro: the same circumstances considered as marks that disținguish a negro from a man of a different fpecies, are denominated modifications.

36. Objects of sight, being complex, are diftinguishable into the several particulars that enter into the composition: these objects are all of them coloured; and they all have length, breadth, and thickness. When I behold a spreading oak, I distinguish in this object, size, figure, colour, and sometimes motion : viewing a flowing river, I distinguish colour, figure, and constant motion: a dye has colour, black spots, six plain surfaces, all equal and uniform. Objects of touch have all of them extension: some of them are felt rough, some smooth: some of them are hard, some soft. With respect to the other senses, some of their objects are simple, fome complex: a found, a taste, a smell, may be so simple as not to be diftinguishable into parts : others are perceived to be compounded of different sounds, different tastes, and different smells.

37. The eye at one look can take in a number

of

en

hann of objects, as of trees in a field, or men in a * crowd: as these objects are distinct from each o* ther, each having a separate and independent exhet istence, they are distinguishable in the mind as Delen well as in reality; and there is nothing more ea. tak i fy, than to abstract from some and to confine our

contemplation to others. A large oak with its ve Spreading branches, fixes our attention upon itles di. self, and abstracts us from the shrubs that surda: round it. In the same manner, with respect to la compound founds, tastes, or smells, we can fix 124. our thoughts upon any one of the component mola parts, abstracting our attention from the rest. licula But the power of abstraction is not confined to

objects that are separable in reality as well as mentally; it also takes place where there can be no real separation : the size, the figure, the colour, of a tree, are inseparably connected, and cannot exist independent of each other; the fame of length, breadth, and thickness: and yet we can mentally confine our observations to one of these, neglecting or abstracting from the rest. Here abstraction takes place where there cannot be a real separation.

38. This power of abstraction is of great utility. A carpenter considers a log of wood, with regard to hardness, firmness, colour, and tex. ture: a philosopher, neglecting these properties, makes the log undergo a chymical analysis; and examines its taste, its smell, and its component principles; the geometrician confines his reason

ing

ing to the figure, the length, breadth, and thickness. In general, every artist, abstracting from all otlier properties, confines his obfervations to those which have a more immediate connection with his profession.

39. Hence clearly appears the meaning of an abstract term, and abstract idea. If in viewing an object, we can abstract from some of its parts or properties, and attach ourselves to others, there must be the fame facility when we recall this object to the mind in idea. This leads direct ly to the definition of an abstract idea, viz.A s partial idea of a complex object, limited to one « or more of the component parts or properties 6 laying aside or abstracting from the rest.” A word that denotes an abstract idea, is called an abstract. term.

40. The power of abstraction is bestowed upon man, for the purposes solely of reasoning. It tends greatly to the facility as well as clearness of any process of reasoning, that, withdrawing from every other circumstance, we can confine our at. tention to the single property we desire to investi. gate.

41. Abstract ideas, may, I think, be distin, guished into three different kinds, all equally fubfervient to the reasoning faculty. Individuals appear to have no end; and did we not possess the faculty of distributing them into classes, the mind would be lost in an endless variety, and no progress be made in knowledge. It is by the fa.

culty

culty of abstraction that we distribute beings into genera and Species: finding a number of individuals connected by certain qualities common to all, we give a name to these individuals.considered as thus connected, which name, by gathering them together into one class, serves in a curt manner to express the whole of these individuals as distinct - from others. Thus the word animal serves to denote every being which hath felf-motion; and the words man, horse, lion,

c. answer similar purposes. This is the first and most common sort of abstraction; and it is of the most extensive use, by enabling us to comprehend in our reasoning whole kinds and forts, instead of individuals without end. The next sort of abstract ideas and terms comprehends a number of individual objects considered as connected by some occasional relation. A great number of persons collected together in one place, without any other relation but merely that of contiguity, are denominated a crowd: in forming this term, we abstract from sex, from age, from condition, from dress, bc. A number of persons connected by being subjected to the same laws and to the same government, are termed a nation : and a number of men subjected to the same military command, are termed an army. A third sort of abstraction is, where a single property or part, which may be common to many individuals, is selected to be the

subject

subject of our contemplation ; for example, whiteness, heat, beauty, length, roundness, head, arm.

42. Abstract terms are a happy invention : it is by their means chiefly, that the particulars which we make the subject of our reasoning are brought into close union, and separated from all others however naturally connected. Without the aid of such terms, the mind could never be kept steady to its proper subject, but would perpetually be in hazard of assuming foreign circumstances, or neglecting what are essential. We can, without the aid of language, compare real objects by intuition, when these objects are present; and, when absent, we can compare them by means of the ideas we have of them. But when we advance farther, and attempt to make inferences, and draw conclusions, we al. ways employ abstract terms, even in thinking: it would be as difficult to reason without them, as to perform operations in algebra without signs; for there is scarce any reasoning without some degree of abstraction, and we cannot abstract to purpose without making use of abstract terms. Hence it follows, that without language man would scarce be a rational being.

43. The same thing, in different respects, has different names. With respect to certain qualities, it is termed a substance; with respect to other qualities, a body; and with respect to qualities of all sorts, a subject. It is termed a pal

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