ideas, he said, was sensation and reflection. If by reflection he meant the observation of the phenomena of the mmd, his theory is one thing. If it mean the process of recalling, combining, ana- lyzing, and otherwise elaborating the impressions upon us from without, his theory is another. Probably Locke himself, and cer- tainly many of his followers, took it in the latter sense ; and thus the two sources of ideas, or of knowledge, are reduced to one, and that one is sensation. But as sensation can give us the knowl- edge only of what is external and material, the theory in this form seemed to leave no room for the higher ideas of eternal and neces- sary truths. Locke attempts to account for our ideas, of time, space, infinity, cause, and even of right and wrong, from observation, i. e., from observation of what is without, or from impressions made upon our senses. It is a common criticism upon Locke's great work, that in it he does not distinguish between the occasion and the source of our ideas. Our experience furnishes the occasion, and it may be the necessary condition, of waking the mind to the perception not only of the fact experienced, but also of the in- tuitive apprehension of the universal and necessary truth which the fact involves. If we did not see effects produced around us, and did not ourselves exercise efficiency, we might never have the idea of causation ; but the conviction that every effect must have a cause is an intuitive judgment, which experience can neither pro- duce nor limit. It is not from the observed tendency of some acts to produce happiness, and of others to produce misery, that we get the idea of the essential distinction between right and wrong ; but from the constitution of the mind. Although Locke, and many of his disciples, were satisfied with his method of accounting for our ideas of God, of spirit, and of moral and I'eligious truths, yet it is also certain that many of his followers felt justified on his princi- ples to discard them.
Rartleij (1705-1757). Hartley was a physician and a physiologist. Physiology and psy- chology have intimate relations. It is perhaps natural that those who devote themselves specially to the former, should make little of the latter. It is the marked characteristic of our age, so fai' as physicists are concerned, that it tries to merge psychology entirely into physiology. Hartley adopted the principles of Locke, and endeavored to show how it is that external things produce sensa- tion and thought. This he did by his theory of vibrations. " The objects of the external world affect in some manner the extreme
260 PART L — THEOLOGY. [Ch. m. — Anti-Theism.
ends of the nerves, which spread from the bram as centre to every part of the body. This affection produces a vibration, w^hich is continued along the nerve by the agency of an elastic ether, until it reaches the brain, where it constitutes the phenomenon we term sensation. When a sensation has been experienced several times, the vibratory movement from which it arises acquires the tendency to repeat itself spontaneously, even when the external object is not present. These repetitions or relics of sensations are ideas, which in their turn possess the property of recalling each other by virtue of mutual association among themselves." ^ This doctrine of asso- ciation of ideas is the most important part of his system. He in- sists principally on the following law : " An idea is sometimes asso- ciated with another through the medium of a third ; but in process of time this intermediate idea may be disregarded, and yet the con- nection between the first and third may, notwithstanding, remain. Thus the idea of pleasure, which is so indissolubly connected with money, arises from the conveniences which it is able to procure, while in the mind of the miser the conveniences are lost sight of, and the veiy possession of the money itself is regarded as containing the whole enjoyment. In this way Hartley accounts for almost all the emotions and passions of the human mind. The domestic affec- tions, for instance, arise from the transference of the pleasure de- rived from parental kindness to the parent itself; the social and pat- riotic affections from transferring the pleasures of society to the country which affords them ; in like manner, also, tlie moral and re- ligious affections, the love of virtue and the love of God, arise from the pleasures connected with virtuous and pious conduct, being transferred to the law of action, or to the supreme LawgiA^er, from whom these pleasures have emanated." ^ The connection of this theory Avitli Materialism is obvious. If vibrations of the brain con- stitute sensation, and if the relics, or spontaneous repetitions of these vibrati<ms constitute thought and feeling, then all mental and moral acts are mere affections of our material organism. It is also obvious that, according to this theory, there is no more freedom in volition than in sensation. The former is a mode, or relic of the latter. Although this tendency of his system was undeniable, and although his successors drew these conclusions from his principles, Hartley himself was not a Materiahst. He was a very religious man. It vs not at all uncommon for a man to hold a speculative theory in- consistent with his faith.
MorelH quotes the following criticism of Hartley's doctrine from
1 Observations on Man, chap. i. sect. 2, and Morell, p. 98. 2 Morel, p. 99.
8 Page 97.