Outline of Sir William Hamilton's philosophy ...

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Preface

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The primary object of this work is to provide a convenient text-book in philosophy. The labors of Sir William Hamilton as a professor formed generally the most powerful influence in the philosophical education of those who came within their reach ; and a similar influence has extended into wider circles through his writings. It seemed to me, therefore, that his philosophy might still be made a valuable instrument of philosophical culture.

The chief difficulty, in the way of this lay in the selection of one of his works, suitable for use as a text-book. A very slight acquaintance with these is sufficient to show that none of them by itself presents a complete view of his philosophical opinions in systematic order. 1 The Lectures on Metaphysics,

1 For many readers it may not be unnecessary to enumerate the works of Sir William Hamilton. (1.) His edition of lieicVs Works (1846) contains, besides many valuable footnotes, a number of supplementary dissertations on various philosophical subjects. Only a few of the intended dissertations were ever completed; but since his death his editors have published the fragmentary materials he had collected for the dissertations which had been left unfinished. (2.) The articles which he had contributed to the Edinburgh Review were collected into one volume, with numerous additions, under the title of Discussions in Philosophy and Literature, Education and University Reform (1852). (3.) The lectures, which he had been in the habit of delivering to his classes, were published posthumously; the Lectures on Metaphysics, in 1859; the

Lectures on Logic, in 1860.

IX

X PREFACE.

which contain the fullest account of his philosophy, and from which, therefore, the largest extracts have been drawn for the present work, besides being devoted mainly to one subdivision of his system, fail to give his matured views, or the matured expression of his views, on some subjects, while the discussion of many points is overladen with a mass of extraneous matter, which is generally confusing to the beginner and unnecessary for the comprehension of Hamilton's own system. I have, therefore, thought it advisable to attempt the systematic exhibition of his philosophical opinions without regard to the order or the mode of treatment which he has followed in any of his writings.

In doing so, however, it was necessary to adopt some order ; and it seemed to me that I had no right to adopt any other than that which the philosopher has himself suggested in his distribution of the philosophical sciences, 1 though he has nowhere been able to carry it out. This distribution may possess comparatively little merit, and has certainly exerted no influence in directing the course of speculative thought in Europe or America, such as has flowed from Hegel's or from Comte's classification of the sciences ; but the system of Hamilton would be inadequately represented by following any other course than that which I have adopted.

With regard to the liberties which I have taken in the composition of this Outline, I may remark, in the first place, that it has frequently been necessary to transfer passages from their original contexts, and that, in doing so, I have introduced them into their new contexts by such connecting particles and phrases as seemed most appropriate. I have

l See Lectures on Metaphysics, VII.

PREFACE. XI

also frequently left out of a passage a feAv words which were not essential to its meaning, especially when they appeared to be intended rather for an audience than for readers. Such slight liberties I have not considered it necessary to indicate. Occasionally, moreover, where Hamilton's editors intimate that he has adopted the language of another writer for the expression of his views, I have not preserved the marks of quotation, as these might have been confusing to a student. In one or two instances, however, I have ventured on an independent or abridged statement of Hamilton's doctrine ; but such passages have been uniformly pointed out in the footnotes. It may also be added that I am responsible for the tabular classifications at pages 83 and 88, as well as for some slight alterations of expression in the others. With these explanations it may be said that the text is wholly Hamilton's.

As an exposition of Hamilton's Philosophy, the Outline contains some imperfections which were unavoidable. Even in the language these may at times be traced : for, while the volume is in the form of a text-book for private study, the largest portion of it is extracted from lectures which were intended to be delivered to a class ; and though I have endeavored to leave out all the most obtrusive expressions of direct address, it was impossible to destroy the general form of phraseology. Some passages, moreover, undoubtedly suffer from being used as an exposition of a doctrine in a different connection and in a different point of view from that in which they were originally written. I believe, however, that no liberty which I have taken in the composition of the book has originated a single misrepresentation of Hamilton's opinions, while the whole volume offers a fair representation of his complete

XII PREFACE.

philosophical system. At the same time I do not take the responsibility of recommending that my book should be accepted as a final authority in any important question concerning Hamilton's doctrine, without referring to the works of the philosopher himself. I have, therefore, uniformly subjoined, within parentheses, a distinct reference to the place in his works from which each passage of the Outline is extracted; and, to prevent mistake, I may observe that each reference embraces the whole passage between it and the previous reference. I am not without hope, therefore, that, while the Outline may serve the purpose for which it is primarily designed, it may also be of some use to those who desire an acquaintance with Sir "William Hamilton's system of philosophy, and have found the state of his writings a formidable obstacle in their way.

I have only to add that the work is merely expository, and that, therefore, while I have avoided any criticism of Hamilton's doctrines, I do not always undertake the responsibility of their defence. I believe, however, that the teaching of philosophy must still, at least, be conducted by helping the student to master the varying points of view from which the different representative systems look out on the field of speculation. For this reason, I trust that a slight service has been rendered to the cause of philosophical education by presenting, with a completeness which has never before been attempted, the system of Sir William Hamilton.

J. CLARK MURRAY.

Contents

PAOB

Introductory Note, by Dr. James McCosh . .' . . xxiii

Introduction

§ 1. The General Nature of Philosophy ...... 19

(A) Nominal Definition of Philosophy 19

(B) Real Definition of Philosophy 20

I. Historical or Empirical Knowledge . . . .21

II. Philosophical or Scientific Knowledge ... 22 Philosophy, strictly so called, is the Science of Mind . 24

§ 2. Classification of the Philosophical Sciences ..... 25

Tabular View of tho Classification 27

FIRST DIVISION OF PHILOSOPHY.

PHENOMENAL PSYCHOLOGY.

Chapter I. Definition Of The Science, And Explanation Of Terms In The Definition

Phenomenal Psychology defined 31

Terms of tho definition explained 31

* XIII

XIV CONTENTS.

(A) Terms expressing the Manifestations of Mind . . .32

(B) Terms expressing the Unknown Basis of Mental Manifesta-

tions 34

Chapter II. Consciousness In General

§ 1. Consciousness: Its General Nature ....... 37

§ 2. Consciousness: Its Special Conditions ...... 40

(A) Undisputed Conditions : — I. It is an actual knowledge.

II. It is an immediate knowledge. III. It supposes discrimination. IV. It involves judgment. V. It implies memory .......... 40

(B) Disputed, whether consciousness is & particular faculty, or the

universal condition, of intelligence . . . .42

I. It cannot be discriminated from the other faculties . 43

II. It is cognizant of their objects, as well as of their

operations 45

§ 3. Consciousness : Its Evidence and Authority ..... 46

(A) It is the principal source from which all knowledge of mental

phenomena must be obtained. — Phrenology ... 47

(B) Authority of its Testimony. — Two points of view, under

which its deliverances may be considered . . . .48

Rules for applying its Testimony . . ■ . . . .53

§4. Consciousness: Classification of its Phenomena . . . .53

I. Knowledges; II. Feelings; III. Conations . . 54

Criticism of Objections to the Classification: I. That the three

classes are not co-ordinate; II. That there can be only

two fundamental powers of mind 56

CONTENTS. XV

FIRST PART OF PHENOMENAL PSYCHOLOGY. PHENOMENOLOGY OF THE COGNITIONS.

INTRODUCTION.

CLASSIFICATION OF THE COGNITIVE FACULTIES.

What is meant by a mental power ........ 61

Distribution of the Faculties of Knowledge 63

Tabular View of the Distribution 66

CHAPTER I.

THE PRESENTATIVE FACULTY.

§ 1. External Perception ......... 67

(A) Distinction between Sensation and Perception ... 68

Law : Sensation and Perception are always in the inverse ratio of each jther 69

Illustration of the Law: I. From a comparison of the different senses ; II. From comparing different impressions of the same sense, as different (1) in degree, (2) in kind 69

(B) Distinction in the Qualities of Matter 73

The qualities as contemplated from the point of view of

Sense and from that of the Understanding ... 74

I. Deduction of the Primary Qualities .... 75

II. Induction of the Secundo-Primary Qualities ... 78

III. Induction of the Secondary Qualities .... 81 Tabular Classification of the Qualities of Matter ... 83 The Object in Perception is either a primary quality or the

quasi-primary phasis of a secundo-primary ... 84 In Perception, therefore, two facts are always given, that I

am, and that something different from me exists . . 86 Theories of Perception, which arise from the acceptance or

non-acceptance of these facts in their integrity . . 87

XVI CONTENTS.

Tabular Classification of these theories .... 88

§2. Self- Consciousness . . . . . . . . . ^ 90

Self-consciousness contrasted with Perception . . . .90

The fundamental forms of Self-Consciousness are Time and Self, as those of Perception are Time and Space. Two difficulties removed 91

CHAPTER II.

THE CONSERVATIVE FACULTY.

The relation of the Conservative Faculty to the Presentative on the one

hand, and to the Reproductive and Representative on the other . 94 § 1. The fact of Retention ......... 96

That Cognitions, in the interval between acquisition and reproduction, continue to subsist in the mind, though out of consciousness, is proved

I. From External Perception, by (1} the Sense of Sight, (2)

the Sense of Hearing, (3) the other Senses . . . .96

II. From the Association of Ideas 99

III. From our Acquired Habits and Dexterities. Three theories to account for these 100

1. That of Hartley and Reid criticised . . .101

2. That of Stewart criticised 102

3. Hamilton's own theory explained . . . . 103 § 2. Explanation of Retention ........ 104

Retention is explained by the self-activity of the mind, the real difficulty being, not how a mental activity endures, but how it ever vanishes 105

Inferences.

1. That Retention extends to all the mental phenomena . . 107

2. That to explain Retention, physiological hypotheses are un-

necessary. Dependence of memory on the state of the brain 107

CONTENTS. XVII

Chapter III. The Reproductive Faculty

Reproduction governed by Laws 110

Distinction between the primary and the secondary Laws of Reproduction 111

§ 1. Primary Laws of Reproduction 112

(A) General.

I. Law of Possible Reproduction .112

II. Laws of Actual Reproduction 112

1. Law of Repetition . . . . . . .114

2. Law of Redintegration 114

(B) Special.

I. Law of Similars 115

II. Law of Contrast 116

III. Law of Coadjacency 117

§ 2. Secondary Laws of Reproduction ....... 117

' General Law of Preference acts 117

(A) By relation to the thought suggesting, giving . . . 118

I. Law of Immediacy 118

II. Law of Homogeneity .118

(B) By relation to the mind, giving the Law of Facility. What

thoughts are more easily suggested 118

§ 3. Distinction of Suggestion and Reminiscence . . . . .120 Reminiscence explained 120

Chapter IV. The Representative Faculty

This faculty is determined to represent by (1) the Reproductive Faculty, (2) the Faculty of Comparison. Imagination

Productive Imagination is therefore Representation plus Comparison Representation is not limited to sensible objects

Dreaming, Somnambulism, Reverie

The Organs of Imagination the same as those of Sense .

126 127 128 128 131

XVIH CONTENTS.

Chapter V. The Elaborativb Faculty

§ 1. Primary Acts of Comparison ....... 134

1. Affirmation of Existence 134

2. Discrimination of the Ego and the Non-ego .... 134

3. Judgment of Agreement or Dissimilarity .... 135

4. Recognition of Substance . . . . . . .135

5. Recognition of Cause 135

(A) Collective Notions 136

(B) Abstraction, poetical and scientific . . . . .138

(C) Generalization; General Notions; Their Extension and Com-

' prehension 140

What is the object of Consciousness, when we employ a general term ? Antagonistic doctrines of the Nominalists and

the Conceptualists 142

Conceptualism originates in ambiguity of terms . . 144

Theories on the question of the Primum Cognitum . . 145

1. That terms are first expressive of individual objects . 145

2. That they first expross classes ..... 146

3. That they first express neither the precisely general nor

the determinately particular, but the vague and confused. (Hamilton's theory) 147

§ 3. Judgment . 150

I. Deductive Reasoning, 1. In Comprehension; 2. In Extension . 153

II. Inductive Reasoning, 1. In Comprehension; 2. In Extension 158 Reasoning, which is synthetic in Extension, is analytic in

Comprehension. Confused application of the terms Analysis

and Synthesis 160

CONTENTS. XIX

Chapter VI. The Regulative Faculty

This faculty is the source of necessary or a priori cognitions . . . 162 Criteria of such cognitions: 1. Incomprehensibility; 2. Simplicity;

3. Necessity and Universality; 4. Certainty .... 164 The conditions of positive thought are: 1. Non-contradiction, and

2. Relativity 165

§ 1. Non-contradiction involves the three laws of : 1. Identity; 2. Contradiction; 3. Excluded Middle 166

§ 2. Relativity implies that we can know neither the unconditionally limited (the Absolute) nor the unconditionally unlimited (tho Infinite), but only the limited, and the conditionally limited. This condition is brought to bear under two relations : . . . 167

(A) The Relation of Knowledge ....... 169

(B) The Relations of Existence, which are either

I. Intrinsic, of Substance and Quality, or . . . 169

II. Extrinsic, comprehending Time, Space, and Degree . 170 Tabular view of the Conditions of Thought 174

Appendix To Chapter VI

LAW OF THE CONDITIONED IN ITS APPLICATION TO THE PRIN- CIPLE OF CAUSALITY.

Statement and Illustration of the principle 173

Theories to explain the principle explained and criticised . . . 177 Tabular view of these theories 180

SECOND PART OF PHENOMENAL PSYCHOLOGY. PHENOMENOLOGY OF THE FEELINGS.

INTRODUCTION.

Relation of the Feelings to the Cognitions on the one hand, and the

Conations on the other 193

XX CONTENTS.

Chapter I. Abstract Theory Of Pleasure And Pain

Definition of Pleasure and Pain 198

Their different kinds : 1. Positive and Negative Pleasure and Pain ;

2. Pain of Restraint and that of Over-exertion .... 199

Chapter II. The Abstract Theory Applied To The Concrete Phenomena

§ 1. The Feelings as 'Causes . . . 200

As Causes the feelings are divided into the pleasurable and the

painful 200

I. The apparent contradictions to the theory in actual life are

really confirmations 200

II. The theory is confirmed by the affections called painful :

(1) Grief; (2) Fear; (3) Pity; (4) Enjoyment of tragedies 202 Four general causes which affect the intensity of our Feelings : I. Novelty; II. Contrast; III. Harmony or Discord between

coexistent activities; IV. Association 203

§ 2. The Feelings as Effects . . ... . . . 20G

As effects of the different energies of life, the feelings may be classified in accordance with the different classes of energies.

(A) The Sensations, or feelings which accompany the exercise of

bodily powers, are divided into (I.) those of Sensus Fixus, and (II.) those of Se?isus Vagus 206

(B) The Sentiments, or feelings which accompany the exercise of

the higher mental powers, comprehend I. The contemplative, the concomitants of our cognitive powers, which are divided into (1) those of the subsidiary faculties; (a) Self-consciousness and (b) Imagination, and (2) those of the elaborative faculty,

CONTENTS. XXI

(a) by itself, (b) in conjunction with imagination. The last include : i. the Beautiful; ii. the Sublime; iii. the Picturesque ....... 208

II. The practical, the concomitants of our conative powers, comprehending those that relate to (1) self-preservation, (2) enjoyment of existence, (3) preservation of the species, (4) our tendency to perfection, (5) the moral law 219

THIRD PART OF PHENOMENAL PSYCHOLOGY. PHENOMENOLOGY OF THE CONATIONS.

Terms to express these phenomena 225

They are divided into

(A) Desires, blind and fatal tendencies to action .... 226

(B) Volitions, free tendencies to action. The freedom of will is

proved (1) directly, (2) indirectly, though it is inconceivable (1) because of the Law of the Conditioned, (2) because motiveless volition is morally unaccountable. But the inconceivability does not invalidate the fact, (1) because the causal judgment is merely a mental impotence, (2) because fatalism is equally inconceivable . . . 226

SECOND DIVISION OF PHILOSOPHY.

NOMOLOGICAL PSYCHOLOGY.

(A) Homology of the Cognitions 231

(B) Homology of the Feelings 232

(C) Nomology of the Conative Powers 233

XXII CONTENTS.

THIRD DIVISION OF PHILOSOPHY.

INFERENTIAL PSYCHOLOGY.

CHAPTER I.

EXISTENCE IN GENERAL.

The axiom, that we have no knowledge of existence itself, but merely of its phenomena, explained in reference to I. Matter, and II. Mind 237

This axiom is divided into two :

I. That the properties of existence are not necessarily of the same

number as our faculties of apprehending them . . . 240

II. That the properties known are not necessarily known in their

native purity . . . . . . . . .242

Certain inferences, however, regarding existence itself may be necessitated by its phenomena 244

CHAPTER II.

EXISTENCE OF GOD AND IMMORTALITY OF THE SOUL.

The notion of a God implies not only Omnipotence, but Intelligence and

Virtue ; and Virtue involves Freedom 247

The proof of God's existence, therefore, requires the proof of two propositions :

I. That the universe is the creation of a free original intelligence 250

II. That the universe is governed not merely by physical, but by

moral, laws 252

Value of mental science to theology 253

Evil influences of the exclusive study of physical science . . . 254 Consequences which would result from referring everything to the

mechanism of nature 256

INTRODUCTORY NOTE.

Sir William Hamilton was the greatest metaphysician of his age, and his metaphysics will be studied by thinking minds in all coming ages. But his system was not drawn out in a compendious form by himself. In order to find it, students have to search a number of treatises in the shape of reviews, dissertations, class-lectures, notes, and notes upon notes. The stablished metaphysician delights in all this as an exhibition of the working of Hamilton's penetrating intellect, and because of the value of the seeds which, in the exuberance of his learning, he scatters in his progress. But as he often moves with great rapidity, and turns off at sharp angles into collateral discussions, the younger student is apt to be left behind and to become perplexed, and he longs to have some guide who may furnish him with a clear and combined view of the philosophy as a whole. This felt want has been supplied in Professor Murray's " Outline of Hamilton's Philosophy."

I have carefully read the work in proof, and I am able to say that it furnishes an admirable summary, — clear, cor-

XXIV INTRODUCTORY NOTE.

rect, and readily intelligible, of the leading doctrines and connections of Hamilton's Philosophy. The account is rendered mainly in Hamilton's own language, by one who understands his philosophy, and who has the higher merit of entering thoroughly into the spirit of his great teacher. I have observed that in points in regard to which there have been disputes as to Hamilton's meaning, Professor Murray seems to me to give the proper version.

Those who are led by this brief exposition to take a general view, as from a height to which Professor Murray has conducted them, of the country spread out before them, will be allured, when he has left them, to enter upon a more particular exploration for themselves, when they will find innumerable scattered ore which could not have a place in a mere Outline.

The testimony now given will not be esteemed of less value because it comes from one who feels that Hamilton has often followed Kant's Critical Method too implicitly, and who dissents from his doctrines of Causality, of the Relativity of Knowledge, and of the negative nature of our Idea of the Infinite.

JAMES McCOSH.

INTRODUCTION.

THE GENERAL NATURE AND DIVISIONS OF PHILOSOPHY.

§ 1. THE GENERAL NATURE OF PHILOSOPHY.

In commencing a course of philosophical discipline, it is important to obtain, at least, a general notion of what philosophy is. In order to this, there are two questions to be answered : (A) What is the meaning of the name? and (£) What is the meaning of the thing?

(A) Nominal Definition of Philosophy. Philosophy is a term of Greek origin, — it is a compound of <p(Xo<;, a lover or friend, and ao<p(a-, wisdom — speculative wisdom. Philosophy is thus, literally, a love of wisdom. But if the grammatical meaning of the word be unambiguous, the history of its application is involved in considerable doubt. According to the commonly received account, the designation of philosopher was first assumed and applied by Pythagoras ; but this rests on very slender authority. It is probable, I think, that Socrates was the first who adopted, or, at least, the first who familiarized, the expression. It was natural that he should be anxious to contradistinguish himself from the Sophists (of ao<poi\ ol <ro<pH7Tou) , literally, the wise men; and no term could more appropriately ridicule the arrogance of these pretenders, or afford a happier contrast to their haughty designation, than that of philosopher (i. e., the lover of wisdom) ; and at the same time it is certain that the substantives <pdo<jo<p[a and <pd6ao<po<; first appear in the writings of the Socratic school. It is true, indeed, that the verb <pdoao<peTv is found in Herodotus (I. 30) ; and that, too, in a participial form, to designate a man who had travelled abroad for the purpose of acquiring knowledge. It is, therefore, not impossible that, before the time of Socrates, those who devoted themselves to the pursuit of the higher branches of knowledge were occasionally designated philosophers ; but it is far more probable that Socrates and his school first appropriated the term as a distinctive appellation ; and that the word philosophy, in consequence of this appropriation, came to be employed for the complement of all higher knowledge, and more especially to denote the science conversant about the principles or causes of existence.

(B) Heal Definition of Philosophy. It is, perhaps, impossible adequately to define philosophy. For what is to be defined comprises what cannot be included in a single definition. For philosophy is not regarded from a single point of view ; it is sometimes considered as theoretical, that is, in relation to man as a thinking and cognitive intelligence ; sometimes as practical, that is, in relation to man as a

Sill WILLIAM HAMILTON 'S PHILOSOPHY. 21

moral agent ; and sometimes as comprehending both theory and practice. Again, philosophy may either be regarded objectively, that is, as a complement of truth known ; or subjectively, that is, as a habit or quality of the mind knowing. In these circumstances I shall not attempt a definition of philosophy, but shall endeavor to accomplish the end which every definition proposes, — make you understand, as precisely as the unprecise nature of the object-matter permits, what is meant by philosophy, and what are the sciences it properly comprehends within its sphere.

All philosophy is knowledge, but all knowledge is not philosophy. Philosophy is, therefore, a kind of knowledge. What, then, is philosophical knowledge, and how is it discriminated from knowledge in general ?

I. We are endowed by our Creator with certain faculties of observation, which enable us to become aware of certain appearances or phenomena. These faculties may be stated as two, — Sense or External Perception, and Self-Consciousness or Internal Perception ; and these faculties severally afford us the knowledge of a different series of phenomena. (1.) Through our senses we apprehend what exists or what occurs in the external or material world ; (2.) By our self-consciousness, what is or what occurs in the internal world or world of thought. The information which we thus receive is called Historical or Empirical knowledge'.

1. It is called historical, because, in this knowledge, we know only the fact, only that the phenomenoil is ; for history is properly only the narration of a consecutive series of phenomena in time, or the description of a coexistent series of phenomena in space. Civil history is an example of the one ; natural history, of the other.

2. It is called empirical or experiential, if we might use that term, because it is given us by experience or observation, and not obtained as the result of inference or reasoning.

Historical or empirical knowledge is, therefore, simply the knowledge that something is. Were we to use the expression, the knowledge that, it would sound awkward and unusual in our modern languages. In Greek, the most philosophical of all tongues, its parallel, however, was familiarly employed. It Was Called to oti, that is, i) yvwaiq or: ecFTtv. I

should notice, that with us the knowledge that, is commonly called the knowledge of the fact. As examples of empirical knowledge, take the facts, whether known in our own experience or on the testified experience of others, that a stone falls, — that smoke ascends, — that the leaves bud in spring, and fall in autumn, — that such a book contains such a passage, — that such a passage contains such an opinion, — that Csesar, that Charlemagne, that Napoleon existed.

II. But things do not exist, events do not occur, isolated — apart — by themselves ; they occur, and are conceived by us, only in connection. Our observation affords us no example of a phenomenon which is not an effect ; nay, our thought cannot even realize to itself the possibility of a phenomenon without a cause. We do not at present inquire into the nature of the connection of effect and cause, either in reality or in thought. It is sufficient for our present purpose to observe that, while, by the constitution of our nature, we are unable to conceive anything to begin to be without referring it to some cause, — still the knowledge of its particular cause is not involved in the knowledge of any particular effect. By this necessity, which we are under, of thinking some cause for every phenomenon ; and by our original ignorance of what particular causes belong to what particular effects, — it is rendered impossible for us to acquiesce in the mere knowledge of the fact of a phenomenon ; on the contrary, we are determined, we are necessitated, to regard each phenomenon as only partially known, until we discover the causes on which it depends for its existence. For example, we are struck with the appearance in the heavens called a rainbow. Think we cannot that this phenomenon has no cause, though we may be wholly ignorant of what that cause is. Now, our knowledge of the phenomenon as a mere fact — as a mere isolated event — does not content us ; we therefore set about an inquiry into the cause, — which the constitution of our mind compels us to suppose, — and at length discover that the rainbow is the effect of the refraction of the solar rays by the watery particles of a cloud. Having ascertained the cause, but not till then, we are satisfied that we fully know the effect.

Now, this knowledge of the cause of a phenomenon is different from, is something more than, the knowledge of that phenomenon simply as a fact ; and these two cognitions or knowledges have, accordingly, received different names. The latter, we have seen, is called historical or empirical knowledge ; the former is called philosophical or scientific or rational knowledge. Historical, is the knowledge that a thing is ; philosophical, the knowledge why or hoio it is. The Greek language well expresses philosophical knowledge as the Stove, — the yvataiq dcort Man.

Such is philosophical knowledge in its most extensive signification ; and in this signification all the sciences occupied in the research of causes may be viewed as so many branches of philosophy. There is, however, one section of these sciences which is denominated philosophical by pre-eminence, — sciences which the term philosophy exclusively denotes, when employed in propriety and rigor. What these sciences are, and why the term philosophy has been specially limited to them, I shall now endeavor to make you understand.

" Man," says Protagoras, " is the measure of the universe : " and in so far as the universe is an object of knowledge, the paradox is a truth. Whatever we know, or endeavor to know, we know and can know only in so far as we possess a faculty of knowing in general ; and we can only exercise that faculty under the laws which control and limit its operations. However great and infinite and various, therefore, may be the universe and its contents, these are known, not as they exist, but as our mind is capable of knowing them.