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studies. No doubt all this is not a science, but without all this there is no science. Such a method would possess not only the advantage of substituting better tendencies for those which actually exist, the study of facts for hypothetical generalizations, it would also offer a task within the reach of all. In this work of detail each might share according to his measure and his strength. Many who could not be architects might cut stones skilfully enough. A hundred workers might perhaps wear themselves out over one obscure point. What matter, if a result be obtained ? The science will accept their work, and forget their names. It will assume its true character—impersonality. Multi pertransibunt, sed augebitur scientia.
IX. We have only a few more words to say, relative to the aim of this work. Since the time of Hobbes and Locke, England has been the country which has done the most for psychology. In our own time two currents of doctrines have been produced there: on one side the a priori school, represented by Sir W. Hamilton, Dr. Whewell, Mr. Mansel, Mr. Ferrier, etc.; on the other, the a posteriori school (Association-Psychology), which numbers among its adherents James Mill, John Stuart Mill, Messrs. Bailey, Herbert Spencer, Bain, Lewes, and several others. A complete
1 Professor Ferrier, of the University of St. Andrews, has published Institutes of Metaphysics in thirty-three propositions : 'one of the most remarkable books of our time,' says Mr. Lewes (a positivist), “but which resembles a solitary obelisk in a vast bare plain. It is remarkable that Professor Ferrier distinguishes experimental psychology very clearly from psychology metamorphosed into metaphysics. • In case,' he says, “it may be thought that psychology has not been sufficiently spared in this work, let it it be remarked that it is only in so much as psychology ventures to treat the fundamental question of knowledge, and to introduce itself into the region of prima philosophia, that it has been criticised and its insufficiency shown. In its own sphere, i.e. the study of mental operations, such as memory, the association of ideas, etc., the labours of psychology ought not to be disdained in any respect.'—Institutes of Metaphysics, p. 116.
* Sir H. Holland, Chapters on Mental Physiology ; Dr. Noble, Medical Psychology ; Brodie, Psychological Enquiries ; Dunn, Physiological Psychology, etc. ; Morell, An Introduction to Mental Philosophy; Maudsley, Pathology and Physiology of Mind; Murphy, Habit and Intelligence, etc. etc.
study of English contemporary psychology would necessarily comprehend both these schools. At present we shall only endeavour to make known the second. As it is unknown, or very nearly unknown, in France, and as it seems to hold the first rank, in virtue of the celebrity of the names which represent it, of its harmony with the general tendencies of the age, and the most recent discoveries of the natural and physical sciences, and of the originality of its researches and results, we believe that it must be useful to make known its doctrines, and that this work of pure exposition cannot be displeasing either to those who accept or to those who repel them.
In considering English contemporaneous psychology, the theories of Hartley have only a retrospective interest. Thus we give him in this instance the place of a precursor merely, for all that is to be found in his work is either left behind or forgotten. Nevertheless, it seems that he has not been done sufficient justice. On the appearance of his Observations on Man, his Frame, his Duty, and his Expectations (1748), the book. had but moderate success. Hartley had preceded its publication, sixteen years previously, by that of a brief Latin treatise, entitled Conjecturæ quædam de Sensu, Motu, et Idearum Generatione. This little work has been republished by Dr. Parr in his Metaphysical Facts by English Philosophers of the Eighteenth Century (1837). But the public, Hartley's contemporaries, seem to have been indifferent to this new manner of conceiving the mechanism of mind. On the other hand, the Association-Psychology, whose theory we propose to explain, is so superior to Hartley, that it is easy to see why that philosopher has almost fallen into oblivion. Nevertheless, as it is a fact that the original idea of associational-psychology is in Hartley, it will be interesting to explain it briefly in this place, were it only to enable us to measure the way which has been made since the Observations on Man.
Hartley is a plain, lucid, methodical writer,—perhaps he is a little too methodical. He proceeds by geometrical method, by propositions, corollaries, and scholia. He divides, subdivides, and distinguishes in a manner worthy of a scholastic. Without losing ourselves in all these subdivisions, let us examine some general points.
The whole of Hartley's system may be resolved into two principal theories :
1. The theory of vibrations, by which he explains all nervous
phenomena, and consequently the relations of the physical and the moral.
2. The theory of association, by which he explains all the mechanism of mind, and all psychological phenomena without exception.
The first is borrowed from Newton's Optics and Principia Philosophia. The second, from Locke's doctrine of the association of ideas, contained in the Essay on the Human Understanding. The following is the explanation of what both consist in.
In order to understand what is new and original in the physiological portion of Hartley's work, we must recall the current universally received ideas of his epoch.
The physicists of the two last centuries habitually resorted, for the explanation of phenomena whose nature was imperfectly known to them, to the intervention of special electric fluids, so defined as to explain those phenomena. Thus they imagined two electric fluids, the one positive, the other negative, and they represented heat, light, and magnetism as other imponderable fluids. They even tried to explain nervous action by the intervention of a new fluid, circulating in the nerves, as if in tubes, and which would be thus conducted from the nervous extremities to the brain.
This doctrine had obtained great credit when Hartley, struck with the important part which the discoveries of Newton attributed to vibrations in optics, and particularly in vision, conceived the idea that an analogous phenomenon must be produced in the cerebro-spinal system. He drew attention to the fact that since a luminous ray, falling upon the eye, determines vibrations in the retina, these vibrations must be propagated by the fibres of the optic nerves, until they reach the brain, in order to produce the sensation of vision, and that they may last for a long time; the same being the case, not only in the sense of sight, strictly speaking, but in the entire nervous system, so that that portion of our organism is in a state of continuous vibration.
But how are these vibrations effected, and in what do they
consist? “They are motions backwards and forwards of the small particles, of the same kind as the oscillation of the pendulum, and the trembling of particles of sounding bodies. They are excited, propagated, and kept up, partly by ether, partly by uniformity and continuity of the brain, spinal marrow, and nerves.'
We perceive that Hartley makes his explanation depend on the hypothesis of the ether, as established by Newton. "Let us suppose the existence of the ether, with its properties, to be destitute of all direct evidence, still, if it serve to explain and account for a great variety of phenomena, it will have an indirect evidence in its favour by those means. We must then conceive the nervous system as penetrated with this elastic compressible substance, apt to receive vibrations. It will therefore follow that the nerves are rather solid capillamenta according to Newton, than small tubuli according to Boerhaave.' Hartley attaches the phenomena of light, heat, sound, attraction, and electricity to his hypothesis of vibrations, very ingeniously.
Thus, the impression of any object upon our organism, disturbance of the nerves, vibrations, transmission of those vibrations to the brain, permanence of vibrations after the sensible object has disappeared, is a summary of the physiological hypothesis of Hartley
We shall not stop to show how insufficient such physiology is. We will only remind our readers that, at that time, the anatomy of the brain and of the nervous system hardly existed. Thus Hartley believes that it is the white substance of the encephalus which presides over the psychological functions, whereas we now know that the grey substance is much the more important of the two. Nevertheless, we cannot deny that he is right upon a number of points. His hypothesis of vibrations, independently of all theories
upon ether and its nature, agrees with the tendencies of modern physics and physiology, which incline to refer everything to movements. Recent researches have shown that there is no nervous fluid, or nervous circulation, such as Hartley's contemporaries believed in, but that impression travels in the nerves in an intermittent manner, like the electric current in a conducting wire. Certain physiologists of our time conceive the mechanism