HARTLEY, DAVID, a celebrated mental philosopher of last century, was b. Aug. 30, 1705. His father was vicar of Armley, in Yorkshire. At 15 he entered Jesus's college, Cambridge, and became a fellow of the college. He studied at first for the church, but his turn for original and independent thinking led him to dissent from some points in the 39 articles, and he, in consequence, had to adandon his original intention. What his precise difficulties were, we are not informed ; we know only that, in his mature years, lie impugned the eternity of hell-punishment, maintaining the ultimate restora tion of the damned. In all other points his published opinions coincided with the church of England, and he continued to the last a member of the church. De filially chose the profession of medicine, in which he attained considerable eminence. Ile practiced as a physician successively at Newark, Bury St. Edmunds, in London, and at Bath, where he died on Aug. 25, 1757, at the age of 52 years.
His work on the mind, entitled Observations on Ilan, on which his fame rests, was begun when he was about 25, and occupied his thoughts for 16 years. It was published in 1749. The first part relates to the constitution of the human mind, and is the really important and original part. The second part treats of religion and morals, and iniedit have been written by any orthodox clergyman, if we except the opinion above stated with reference to future punishment.
His handling of the mind turns throughout upon two theories or hypotheses, which have very different merits, and are by no means necessarily conjoined, although they are never separated in his mind. The first is called the doctrine of vibrations, or a theory of nervous action analogous to the propagation of sound, the suggestion of which he owed to Newton, of whose writings he was a devoted student. His second and most valuable innovation consisted in showing that the faculties, powers, and feel ings of the mind might he explained to a very wide extent by tire principle of the association of ideas (see ASSOCIATION OF IDEAS), a principle far from new in the state ment of it, but never before appreciated in anything like the range of its bearings upon the phenomena of mind.
The doctrine of vibrations supposed that when any one of the senses is affected by an outward object, the effect was to set the particles of tire nerve in a vibratory motion, which ran along to the brain, and produced corresponding vibrations in the cerebral Substance. In like manner, when an active impulse proceeded outwards to the muscles.
the manner of communication along the nerves was of the same kind. Ile even extended these molecular vibrations to the other tissues. As a hypothesis, this assump tion was so far legitimate, if it served to explain the facts, or even to imagine in a probable way what goes on in the substance of the nerves and brain during the pro cesses of sensation, thought, and volition. The distaste that has generally been entertained towards this part of Hartley's speculations, arose from a mistaken notion of its favoring materialism. Not only was the author not a materialist—being most express m affirming a spiritual entity different from the body—but his views had nothing more of materialism in them than the views that mankind have always held as to the connection of mind with bodily actions.
As regards the second doctrine of Hartley, the doctrine of association, he was cer tainly the first to do justice to the applications of that principle to explain the phenomena of the mind. He points out how it is involved in the conversion of our sensations into ideas, throughout all the senses, and also in the first origin of voluntary power,. which he truly regards as essentially an acquired power. He then treats of the commonly recognized intellectual faculties—memory, imagination, reason, etc.—show ing how widely the process -of association pervades them all. Lastly, the emotions, which he classifies under 6 heads—imaginative emotions, ambition, self-interest, sym pathy, theopathy, (the religious sentiment), and the moral sense—may be readily seen to be, in a great many instances, the products of association, there being certain elemen tary feelings that unite among themselves, and pass into new connections, and give birth to complex feelings, under the general law. Many of those explanations would be considered now as faulty or defective ; but at the time, Hartley's attempt was a great step in advance, and might have been much more fruitful in consequences to mental science, but for the unfortunate and mistaken prejudice excited by the vibra tion theory, which lie carries out into every part of his exposition. •