protect their weakness. Chased from the open country, these robbers fly into the forest, and lie in wait to break in upon every unguarded avenue of the mind and overwhelm it with religious fears and prejudices. The stoutest antagonist, if he remits his watch a moment, is oppressed; and many, through cowardice and folly, open the gates to the enemies, and willingly receive them with reverence and submission as their legal soveregins.

"But is this a sufficient reason why philosophers should desist from such researches and leave superstition still in possession of her retreat? Is it not proper to draw an opposite conclusion, and perceive the necessity of carrying the war into the most secret recesses of the enemy? . . The only method of freeing learning at once from these abstruse questions, is to inquire seriously into the nature of human understanding, and show, from an exact analysis of its powers and capacity, that it is by no means fitted for such remote and abstruse subjects. We must submit to this fatigue, in order to live at ease ever after; and must cultivate true metaphysics with some care, in order to destroy the false and adulterated." (IV. pp. 10, 11.)

Near a century and a half has elapsed since these brave words were shaped by David Hume's pen; and the business of carrying the war into the enemy's camp has gone on but slowly. Like other campaigns, it long languished for want of a good base of operations. But since physical science, in the course of the last fifty years, has brought to the front an inexhaustible supply of heavy artillery of a new pattern, warranted to drive solid bolts of fact through the thickest skulls, things are looking better; though hardly more than the first faint flutterings of the dawn of the happy day, when superstition and false metaphysics shall be no more and reasonable folks may "live at ease," are as yet discernible by the enfants perdus of the outposts.

If, in thus conceiving the object and the limitations of philosophy, Hume shows himself the spiritual child and continuator of the work of Locke, he appears no less plainly as the parent of Kant and as the protagonist of that more modern way of thinking, which has been called agnosticism," from its profession of an incapacity to discover the indispensable conditions of either positive or negative knowledge, in many propositions, respecting which, not only the vulgar, but philosophers of the more sanguine sort, revel in the luxury of unqualified

assurance.

The aim of the Kritik der reinen Vernunft is essentially the same as that of the Treatise of Human Nature, by which indeed Kant was led to develop that "critical philosophy" with which his name and fame are indissolubly bound up: and, if the details of Kant's criticism differ from those of Hume, they coincide with them in their main result, which is the limitation of all knowledge of reality to the world of phenomena revealed to us by experience.

The philosopher of Königsberg epitomises the philosopher of Ninewells when he thus sums up the uses of philosophy :

"The greatest and perhaps the sole use of all philosophy of pure reason is, after all, merely negative, since it serves, not as an organon for the enlargement [of knowledge], but as a discipline for its delimitation; and instead of discovering truth, has only the modest merit of preventing error."1

1 Kritik der reinen Vernunft. Ed. Hartenstein, p. 256.

CHAPTER II.

THE CONTENTS OF THE MIND.

In the language of common life, the "mind" is spoken of as an entity, independent of the body, though resi dent in and closely connected with it, and endowed with numerous "faculties," such as sensibility, understanding, memory, volition, which stand in the same relation to the mind as the organs do to the body, and perform the functions of feeling, reasoning, remembering, and willing. Of these functions, some, such as sensation, are supposed to be merely passive-that is, they are called into existence by impressions, made upon the sensitive faculty by a material world of real objects, of which our sensations are supposed to give us pictures; others, such as the memory and the reasoning faculty, are considered to be partly passive and partly active; while volition is held to be potentially, if not always actually, a spontaneous activity.

The popular classification and terminology of the phenomena of consciousness, however, are by no means the first crude conceptions suggested by common sense, but rather a legacy, and, in many respects, a sufficiently damnosa hæreditas, of ancient philosophy, more or less

leavened by theology; which has incorporated itself with the common thought of later times, as the vices of the aristocracy of one age become those of the mob in the next. Very little attention to what passes in the mind is sufficient to show, that these conceptions involve assumptions of an extremely hypothetical character. And the first business of the student of psychology is to get rid of such prepossessions; to form conceptions of mental phenomena as they are given us by observation, without any hypothetical admixture, or with only so much as is definitely recognised and held subject to confirmation or otherwise; to classify these phenomena according to their clearly recognisable characters; and to adopt a nomenclature which suggests nothing beyond the results of observation. Thus chastened, observation of the mind makes us acquainted with nothing but certain events, facts, or phenomena (whichever name be preferred) which pass over the inward field of view in rapid and, as it may appear on careless inspection, in disorderly succession, like the shifting patterns of a kaleidoscope. To all these mental phenomena, or states of our consciousness,1 Descartes gave the name of "thoughts," 2 while Locke

1

"Consciousnesses" would be a better name, but it is awkward. I have elsewhere proposed psychoses as a substantive name for mental phenomena.

2 As this has been denied, it may be as well to give Descartes's words: "Par le mot de penser, j'entends tout ce que se fait dans nous de telle sorte que nous l'apercevons immédiatement par nousmêmes c'est pourquoi non-seulement entendre, vouloir, imaginer, mais aussi sentir, c'est le même chose ici que penser."-Principes de Philosophie. Ed. Cousin. 57.

:

"Toutes les propriétés que nous trouvons en la chose qui pense ne sont que des façons différentes de penser."—Ibid. 96.

Hume, regarding "idea," for which

and Berkeley termed them "ideas." this as an improper use of the word he proposes another employment, gives the general name of "perceptions" to all states of consciousness. Thus, whatever other signification we may see reason to attach to the word "mind," it is certain that it is a name which is employed to denote a series of perceptions; just as the word "tune," whatever else it may mean, denotes, in the first place, a succession of musical notes. Hume, indeed, goes further than others when he says that

"What we call a mind is nothing but a heap or collection of different perceptions, united together by certain relations, and supposed, though falsely, to be endowed with a perfect simplicity and identity."-(I. p. 268.)

With this "nothing but," however, he obviously falls into the primal and perennial error of philosophical speculators-dogmatising from negative arguments. He may be right or wrong; but the most he, or anybody else, can prove in favour of his conclusion is, that we know nothing more of the mind than that it is a series of perceptions. Whether there is something in the mind that lies beyond the reach of observation; or whether perceptions themselves are the products of something which can be observed and which is not mind; are questions which can in nowise be settled by direct observation. Elsewhere, the objectionable hypothetical element of the definition of mind is less prominent :

"The true idea of the human mind is to consider it as a system of different perceptions, or different existences, which