Philosophy. — Hartley neither proclaimed nor pro- duced any scheme of specidation, nor did he pretend that his views were characterized by any marked de- gree of originality. He investigated and endea\-ored to explain certain phenomena of the human mind, and to discover the machinery of thought. He has be- queathed a doctrine which has been ui part generally adopted, and which has been frequently exaggerated by admirers who have repudiated, ignored, or been ig- norant of the characteristic ground-work on which it had been erected. Tlie source and filiation of his tenets have been indicated by him with what Su- James Mack- intosh conceives to have been extravagant generosity. Hartley's acknowledgments are, however, made in igno- rance of his much larger, liut more remote obligations to Aristotle. "About eighteen years ago," says he, in
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the preface of his work, " I was informed that the Rev. Mr. (iay, then living, asserted the possibilitj- of deduc- ing aU our intellectual pleasures and pains from associa- tion. This put me upon considering the power of asso- ciation. I5y degrees many disquisitions foreign to the doctrine of association, or, at least, not immediately connected with it, intermixed themselves." " I think, however, that I cannot be called a system maker, since I did not first form a system, and then suit the facts to it. but was carried on by a train of thoughts from one thing to another, frequently without any express de- .sign, or even any previous suspicion of the consequences that might arise." Assuredly this is neither a syste- matic nor a philosophical method of procediure. But this easy disagation of thought explains the instability, want of consistency, and partial incoherence of Hart- ley's speculations. It also explains the facility and un- Hiispectcd inconsequence with which a portion of the doctrine has been separated from its accompaniments for special acceptance and development.
The characteristic tenets of Hartley have been very clearly and concisely stated by Morell. "The objects t)f the external world affect in some manner the extreme ends of the nerves, which spread from the brain as a centre to every part of the bodj'. This affection pro- duces a vibration, which is continued along the nerve by the agency of an elastic ether until it reaches the brain, where it produces the phenomenon we term sen- sation. When a sensation has been experienced several times, the vibratory movement from which it arises ac- quires the tendency to repeat itself spontaneously, even when the external object is not present. These repeti- tions, or relics of sensation, are ideas, which in their turn possess the property of recalling each other by vir- tue of mutual association among themselves
The subordinate effects of these principles are easy to be imagined. If all our ideas are but relics of sensa- tions, and all excited spontaneously by the laws of asso- ciation, it is abundantly evident that the power of the will must l)e a nonentity, that man can really have no control of his own mind, that he is the creature of irre- sistible necessity. Hartley was accordingly a firm nec- essarian. Another natural effect of the theorj-^ of vibra- tions is materialism." The pernicious consequences of their dogmas arc perspicaciously displayed by Coleridge, who had at one time been so devoted to their teachings tjiat he bestowed the name of their author upon his son, Hartley Coleridge.
lu this si>eculation there are three distinct but inti- mately connected doctrines. 1. The theory of the asso- ciation of ideas. '2. The physiological and physical mode of accounting for this association and for percep- tion by tiie vibrations of an elastic ether through the medullary substance of the nerves. 3. The assertion of the necessity of human actions. The last of these con- nects itself with the optimism of Leibnitz and the fatal- ism of Spinoza, through King's Oriyin of Evil. The second dogma was early abandoned, at least in the form in wliich it was presented by this author. It was not entirely novel, but it Avas the most original portion of Hartley's labors, and through it he mainly influenced the devel(>i)mcnt of the French i)hilosophy. It was suggested by one of the queries in Newton's Optics, and may be traced tlirough the animal spirits of Locke and I)cs Cartes, and the vortices and elastic ether of Des Cartes to the earlier philos<iphers, and up to Epicurus and Leucippus. It may merit renewed consideration if the physiological jisychology now in prospect should gain acce]>tance. Tiio doctrine of Association is re- garded as being peculiarly Hartley's own. It was not altogether novel: he himself ascribes its first suggestion to (iay. It is jiresupposed in many suggestions of I^)c'ke, and is descende(l from a more remote and illus- trious ancestry, which runs back to the Stag\Tite — the reimted fountain of so much error, the father of so much wisdom. It recei\-ed, however, such an ingenious and extensive development from Hartley that Sir James
Mackintosh rightly disregards the claims of Gay, but wrongly neglects earlier obligations. It is largely in- corporated into recent schemes of metaphj'sics, ethics, and {esthetics, but severed from the mechanical hA-jioth- esis which gave it its chief originality and its distinc- tive complexion. In this mutilated form it possesses unquestionable truth ; but still it is only an imperfect explanation of a limited class of mental and moral phe- nomena, and is easily pressed, as it has often been push- ed, to absurd and hazardous conclusions. Coleridge has forcibly signalized its dangers, and has declared that, wherever it deviates from the simpler exposition of Aris- totle, it declines into error and immoral courses.