doubtful. The literature of the day was drenched, with metaphors taken from the dominant science. Fashion, after a long interval, once more patronized Nature, and the "bottle-and-squirt mania" spread. Experimentalism in Psychology was still under a cloud, from the discredit which had attached to the premature theorizing of Hartley. But in the early part of the century, Dr. Thomas Brown had gained a hearing, under cover of the respectable orthodoxy of the Scotch universities, for speculations thickly sown with revolutionary germs. One of his pupils was James Mill, and in 1829 that resolute and thorough-going, if narrow and aggressive, thinker published the treatise which marked the turn of the tide. Deriving his inspiration from the neglected work of Hartley, gathering up the hints freely scattered in Brown's lectures, and imbued with the spirit of the prevailing chemistry, he set about constructing a new science of mind, of which the physics should not be obsolete, and which should push the analysis of the accepted metaphysical mysteries to the farthest possible limit. He obeyed the double analytic and synthetic movement in contemporary chemical investigation. As specimens of his analytical advance, we may point to his further resolution of the apparently simple ideas of hardness and extension, which had been begun by Hartley and continued by Darwin.[1] But, as better illustrating the dynamical influence of physical science, we prefer to lay emphasis on what may, as it appears to us, be justly styled his synthetical contribution to Psychology. This was his conception, applied to the whole range of mental phenomena, of the chemical nature of association. Quite to realize the new shape which the welding mental power took in his hands, we must glance back at its history. It is comparatively young. Hobbes knew nothing of it: his "synthesis," by which things are "constructed or generated," is purely geometrical,[2] and with him association is mere sequence.[3] Locke's advance on this is clear, though inconsiderable: he speaks of the "tying together of ideas," and describes certain ideas as appearing in "gangs, always inseparable,"[4] but he regards "mixed modes" as made by men voluntarily with a view to communication.[5] Hartley, according to Mr. J. S. Mill, had reached the stage we have above stated as only attained by James Mill:
"It was reserved for Hartley to show that mental phenomena, joined together by association, may form a still more intimate, and as it were chemical union; . . . the compound having all the appearance of a phenomenon sui generis, as simple and elementary as the ingredients, and with properties different from any of them."[6]
This is far too strongly stated. That the union of the associated mental elements as conceived by Hartley was more intimate than their mode of conjunction as conceived by Locke, or their rigidity of sequence
