LITMIR.BIZ

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to all reasoning on the subject, for, when we give up consciousness as no longer reliable, there is nothing left to fall back upon. If any one chooses to leap from this precipice, we can only say finis.

      § VII.—HISTORICAL SKETCH.

      I. Of Different Divisions of the Qualities of Bodies.

      The Greek Philosophers.—The distinction of the qualities of bodies into two classes, differing in important respects, is by no means a modern one. It was recognized by some of the earlier Greek philosophers, who held that the sweet, bitter, hot, cold, etc., are rather affections of our own senses than proper qualities of matter, having independent existence. Subsequently the view was adopted by Protagoras, and by the Cyrenean and Epicurean schools. Plato held it, and especially and very fully, Aristotle, who calls the qualities to which we have referred, and which are usually denominated secondary, affective qualities, because they have the power of affecting the senses, while the qualities now usually termed primary, as extension, figure, motion, number, etc., he regards as not properly objects of sense. The former class he calls proper sensibles, the latter, common.

      The Schoolmen.—The schoolmen made much of this distinction, and held, with Aristotle, that the qualities now called primary, require, for their cognition, other faculties than those of sense.

      Doctrine of Galileo.—Galileo points out the true ground and philosophy of this distinction, and also gives the name primary to the class referred to, viz., those qualities which are necessary to our conception of body, as for example, figure, size, place, etc., while, on the contrary, colors, tastes, etc., are not inherent in bodies, but only in us, and we can conceive of body without them. The former are real qualities of bodies, while the latter are only conceptions which give us no real knowledge of any thing external, but only of the affections of our own minds.

      The Moderns.—Descartes and Locke merely adopted these distinctions as they found them, without essential modification. So also did Reid and Stewart, although both included among the primary qualities some which are properly secondary, as roughness, smoothness, hardness, softness. Indeed Stewart restricted the primary qualities to those and such as those just named.

      Hamilton.—No writer has so fully elaborated this matter as Sir William Hamilton, to whom we are indebted mainly for the historical facts now stated, and whose dissertations are and must ever remain an invaluable thesaurus on the philosophy of perception. So complete and elaborate is his classification of the qualities of matter, that I shall be pardoned for giving a synopsis of its principal points in this connection.

      Hamilton's Scheme—General Divisions.—He divides the qualities of bodies into three classes, which he calls primary, secundo-primary, and secondary. The primary are thought as essential to the very notion of matter, and may be deduced à priori, the bare notion of matter being given; while the secundo-primary and the secondary, being accidental and contingent, must be deduced à posteriori, learned by experience. His deduction of the primary qualities is as follows:

      Primary Qualities.—We can conceive of body only as, I. Occupying space; II. Contained in space. Space is a necessary form of thought, but we are not obliged to conceive of space as occupied, that is, to conceive of matter. When conceived it must be under the conditions now named.

      I. The property of occupying space is Simple Solidity, which implies, a. Trinal extension, or length, breadth, and thickness; b. Impenetrability, or the property of not being reduced to non-extension. Trinal extension involves, 1. Number, or Divisibility; 2. Size, including Density; 3. Shape.

      II. The attribute of being contained in space, affords the notion, 1. Of Mobility; 2. Of Position.

      The essential and necessary constituents then of our notion of matter are, 1. Extension (comprising under it, 2. Divisibility; 3. Size; 4. Density; 5. Figure); 6. Ultimate Incompressibility; 7. Mobility; 8. Situation. These are the primary qualities, products, in a sort, of the understanding, developing themselves with rigid necessity out of the given notion of substance occupying space.

      Secundo-Primary Qualities.—The secundo-primary are contingent modifications of the primary, all have relation to space, and motion in space, all are contained under the category of resistance, or pressure, all are learned or included as results of experience, all have both an objective and subjective phase, being at once qualities of matter, and also affections of our senses.

      Considered as to the sources of resistance, there is, I. That of Co-attraction, under the forms of a, Gravity, b, Cohesion; II. That of Repulsion; III. Inertia; all which are capable of minute subdivision. Thus from cohesion follow the hard and soft, firm and fluid, tough and brittle, rigid and flexible, rough and smooth, etc., etc. From repulsion are derived compressible and incompressible, resilient and irresilient.

      Secondary Qualities.—The secondary qualities are, as apprehended by us, not properly attributes of body at all, but only affections of our nervous organism. They belong to bodies only so far as these are furnished with the power of exciting our nervous organism to the specific action thus designated. To this class belong color, sound, flavor, savor, tactile sensation, feeling of heat, electricity, etc. Such also are titillation, sneezing, shuddering, and the various sensations, pleasurable or painful, resulting from the action of external stimuli.

      These Classes further distinguished.—Of the qualities thus derived, the primary are known immediately in themselves, the secondary only mediately in their effects on us, the secundo-primary both immediately in themselves, and mediately in their effects on us. The primary are qualities of body in relation to body simply, and to our organism as such; the secundo-primary are qualities of body in relation to our organism, not as body in general, but as body of a particular sort, viz.: propelling, resisting, cohesive; the secondary are qualities of body in relation to our organism as excitable and sentient. The primary may be roundly characterized as mathematical, the secundo-primary as mechanical, the secondary as physiological.

      Reasons for retaining the twofold Division.—Such, in brief outline, are the principal points of Hamilton's classification. While following in the main the distinctions here indicated, I have preferred to retain the old division into primary and secondary, as at once more simple, and sufficiently accurate, merely dividing the secondary into two classes, the mechanical (secundo-primary of Hamilton), and physiological. We are thus enabled, not merely to retain a division and nomenclature which have antiquity and authority in their favor, and are well-nigh universally received, but we avoid the almost barbarous terminology of Sir William's classification—while, at the same time, we indicate with sufficient precision the important distinction between the so-called secundo-primary and secondary qualities.

      II. Of Different Theories of Perception.

      Realists and Idealists.—There are two leading theories, quite distinct from each other, which have widely prevailed, and divided the thinking world, as to the philosophy of perception. The one maintains that in perception we have direct cognizance of a real external world. This is the view taken in the preceding pages, and now generally held by psychologists in this country, and to some extent in Europe But for a long period, the prevalent, and in fact, until the time of Reid in Scotland, and Kant in Germany, the almost universally-received opinion was the reverse of this—that in perception, as in any and all other mental acts, the mind is conscious only of its own ideas, cognizant of itself and its own states only, incapable, in fact, of knowing any thing external to itself. Those who hold the former view are termed Realists, the latter Idealists.

      Further division of the latter.—The latter, however, are of two classes. The Absolute Idealists hold that the notion we have of external things is purely subjective, having no external counterpart, no corresponding outward reality. In distinction from this the greater part maintain that while we are cognizant, directly and strictly, of nothing beyond our own minds, nevertheless there is an external reality corresponding to the idea in our minds, and which that idea represents. Hence they have been designated Representative Idealists, or, as Sir William Hamilton terms them, Cosmothetic Idealists.

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