There have been men in all ages, who have been impelled as by an instinct to propose their own nature as a problem, and who devote their attempts to its solution. The first step was to construct a table of distinctions, which they seem to have formed on the principle of the absence or presence of the Will. Our various sensations, perceptions, and movements were classed as active or passive, or as media partaking of both. A still finer distinction was soon established between the voluntary and the spontaneous. In our perceptions we seem to ourselves merely passive to an external power, whether as a mirror reflecting the landscape, or as a blank canvass on which some unknown hand paints it. For it is worthy of notice, that the latter, or the system of Idealism may be traced to sources equally remote with the former, or Materialism; and Berkeley can boast an ancestry at least as venerable as Gassendi or Hobbes. These conjectures, however, concerning the mode in which our perceptions originated, could not alter the natural difference of Things and Thoughts. In the former, the cause appeared wholly external, while in the latter, sometimes our will interfered as the producing or determining cause, and sometimes our nature seemed to act by a mechanism of its own, without any conscious effort of the will, or even against it. Our inward experiences were thus arranged in three separate classes, the passive sense, or what the School-men call the merely receptive quality of the mind; the voluntary; and the spontaneous, which holds the middle place between both. But it is not in human nature to meditate on any mode of action, without inquiring after the law that governs it; and in the explanation of the spontaneous movements of our being, the metaphysician took the lead of the anatomist and natural philosopher. In Egypt, Palestine, Greece, and India the analysis of the mind had reached its noon and manhood, while experimental research was still in its dawn and infancy. For many, very many centuries, it has been difficult to advance a new truth, or even a new error, in the philosophy of the intellect or morals. With regard, however, to the laws that direct the spontaneous movements of thought and the principle of their intellectual mechanism there exists, it has been asserted, an important exception most honourable to the moderns, and in the merit of which our own country claims the largest share. Sir James Mackintosh,--(who, amid the variety of his talents and attainments, is not of less repute for the depth and accuracy of his philosophical inquiries than for the eloquence with which he is said to render their most difficult results perspicuous, and the driest attractive,)--affirmed in the Lectures, delivered by him in Lincoln’s Inn Hall, that the law of association as established in the contemporaneity of the original impressions, formed the basis of all true psychology; and that any ontological or