II. Intimately connected with the physiological hypothesis of the Hartleian school, is their metaphysical theory of Association, from which single principle they boast to have explained synthetically all the phenomena of the mind. In Dr. Priestley's Remarks on Reid's Inquiry, there is an attempt to turn into ridicule, by what the author calls a Table of Dr. Reid's Instinctive Principles, the application of the Inductive Logic to these phenomena. How far this Table is faithfully extracted from Dr. Reid's book, it is unnecessary for me to consider at present.* Supposing, for the sake of argument, that the Twelve Principles enumerated by Priestley had been actually stated by his antagonist as instinctive principles, or as general laws of our nature, it is difficult to see for what reason the enumeration should be regarded as absurd, or even as unphilosophical, after the explanation given by Reid himself of the sense in which he wished his conclusions to be understood.

"The most general phenomena we can reach, are "what we call Laws of Nature. So that the laws of na"ture are nothing else but the most general facts relating "to the operations of nature, which include a great many "particular facts under them. And, if, in any case, we

pears plainly, from his Queries, to have imbibed also some of the physiological theories of his preceptor.

In the Monthly Review for 1808, I observe the following passage: "For the partiality which he (Dr. Cogan) shews to Dr. Reid, we "may easily account, as being a just tribute to the ingenuity and “industry of that writer, and to the numerous valuable observations "which enrich his works, unconnected with his crude hypothesis on "the subject of the Human Mind." In what part of Dr. Reid's writings is this crude hypothesis proposed?

• The reader will be enabled to form a judgment on this point, by the Note (**) at the end of this Volume.

B

"should give the name of a law of nature to a general phenomenon, which human industry shall afterwards "trace to one more general, there is no great harm done.. "The most general assumes the name of a law of nature "when it is discovered; and the less general is contained "and comprehended in it."*

In another part of his work, he has introduced the same remark."The labyrinth may be too intricate, and the "thread too fine, to be traced through all its windings; "but if we stop where we can trace it no farther, and "secure the ground we have gained, there is no harm "done; a quicker eye may in time trace it farther."†

In reply to these passages, Priestley observes, that "the suspicion that we are got to ultimate principles, "necessarily checks all farther inquiry, and is therefore "of great disservice in philosophy. Let Dr. Reid (he "continues) lay his hand upon his breast, and say, whe"ther, after what he has written, he would not be exceed. 'ingly mortified to find it clearly proved, to the satisfac"tion of all the world, that all the instinctive principles "in the preceding Table were really acquired; and that "all of them were nothing more than so many different cases of the old and well-known principle of Associa "tion of Ideas."

With respect to the probability of this supposition, I have nothing to add to what I have stated on the same head, in the Philosophy of the Human Mind; "that, in

all the other sciences, the progress of discovery has "been gradual, from the less general to the more general "laws of nature; and that it would be singular indeed, if,

Reid's Inquiry, p. 223, 3d ed.

† P. 9.

"in this science, which but a few years ago was confessedly in its infancy, and which certainly labours under many disadvantages peculiar to itself, a step should all "at once be made to a single principle, comprehending "all the particular phenomena which we know."*

As the order established in the intellectual world seems to be regulated by laws perfectly analogous to those which we trace among the phenomena of the material system; and as, in all our philosophical inquiries (to whatever subject they may relate) the progress of the mind is liable to be affected by the same tendency to a premature generalization, the following extract from an eminent chemical writer may contribute to illustrate the scope, and to confirm the justness of some of the foregoing reflections. "Within the last fifteen or twenty years, several new "metals, and new earths, have been made known to "the world. The names that support these discoveries "are respectable, and the experiments decisive. If we "do not give our assent to them, no single proposition "in chemistry can for a moment stand. But whether "all these are really simple substances, or compounds "not yet resolved into their elements, is what the authors "themselves cannot possibly assert; nor would it, in the least, diminish the merit of their observations, if future

experiments should prove them to have been mistaken, "as to the simplicity of these substances. This remark "should not be confined to later discoveries; it may as "justly be applied to those earths and metals with which "we have been long acquainted."-" In the dark ages, "of chemistry, the object was to rival nature; and the

Elements, &c. p. 398 (3d edition), where I have enlarged on this point at some length.

"substance which the adepts of those days were basied "to create, was universally allowed to be simple. In a "more enlightened period, we have extended our inqui"ries, and multiplied the number of the elements. The "last task will be to simplify; and, by a closer obser"vation of nature, to learn from what a small store of 66 primitive materials, all that we behold and wonder at "was created."*

This analogy between the history of chemistry and that of the philosophy of the human mind, which has often struck myself in contrasting the views of the Alchemists with those of Lavoisier and his followers, has acquired much additional value and importance in my estimation, since I had the pleasure to peruse a late work of M. De Gerando; in which I find, that the same analogy has presented itself to that most judicious philosopher, and has been applied by him to the same practical purpose, of exposing the false pretensions and premature generalizations of some modern metaphysicians.

"It required nothing less than the united splendour of "the discoveries brought to light by the new chemical "school, to tear the minds of men from the pursuit of a "simple and primary element; a pursuit renewed in every

age with an indefatigable perseverance, and always re"newed in vain. With what feelings of contempt would "the physiologists of former times have looked down on "the chemists of the present age, whose timid and cir"cumscribed system admits nearly forty different prin

* Inquiries concerning the nature of a metallic substance, lately sold in London as a new Metal, under the title of Palladium. By Rich. Chenevix, Esq.

*ciples in the composition of bodies! What a subject of "ridicule would the new nomenclature have afforded to "an Alchemist!"

"The Philosophy of Mind has its Alchemists also; men whose studies are directed to the pursuit of one single principle, into which the whole science may be "resolved; and who flatter themselves with the hope of discovering the grand secret, by which the pure gold of "Truth may be produced at pleasure."*

Among these Alchemists in the science of mind, the first place is undoubtedly due to Dr. Hartley, who not only attempts to account for all the phenomena of human nature, from the single principle of Association, combined with the hypothetical assumption of an invisible fluid or ether, producing Vibrations in the medullary substance of the brain and nerves; but indulges his imagination in anticipating an æra," when future generations shall put "all kinds of evidences and inquiries into mathemetical "forms; reducing Aristotle's ten categories, and Bishop "Wilkins' forty summa genera, to the head of Quantity "alone, so as to make mathematics and logic, natural "history and civil history, natural philosophy, and philo"sophy of all other kinds, coincide omni ex parte." If I had never read another sentence of this author, I should have required no farther evidence of the unsoundness of his understanding.

It is however, on such rash and unwarranted assertions as this, combined with the supposed comprehensiveness of his metaphysical views, that the peculiar merits of Hartley seem now to be chiefly rested by the more en

De Gerando, Hist. des Systemes, tom. II. pp. 481, 482.