After considering the Phenomena of the Mind _in general_, we are now to proceed to consider them, in the _separate classes_ in which they may be arranged. The phenomena themselves, indeed, are almost infinite, and it might seem, on first reflection a very hopeless task, to attempt to reduce, under a few heads, the innumerable feelings, which diversify almost every moment of our life. But to those, who are acquainted with the wonders, which classification has performed, in the other sciences, the task, difficult as it is, will still seem not absolutely hopeless; though in one respect, its difficulty will be more highly estimated by them, than by others;--since _they_ only, who know the advantage of the fixed and definite nature of the objects of classification, in other _sciences_, can feel, how much greater the obstacles must be, to any accurate arrangement, in a science, of which the objects are indefinite, and complex, incapable of being fixed for a moment in the same state, and destroyed by the very effort to grasp them. But, in this, as in other instances, in which nature has given us difficulties with which to cope, she has not left us to be wholly overcome; or, if we must yield, she has at least armed us for so vigorous a struggle, that we gain additional intellectual strength, even in being vanquished. “Studiorum salutarium, etiam citra effectum, salutaris tractatio est.” If she has placed us in a labyrinth, she has at the same time furnished us with a clue, which may guide us, not indeed through all its dark and intricate windings, but through those broad paths, which conduct us into day. The single power, by which we discover resemblance or relation in general, is a sufficient aid to us, in the perplexity and confusion of our first attempts at arrangement. It begins, by converting thousands, and more than thousands, into one, and, reducing, in the same manner, the numbers thus formed, it arrives at last at the few distinctive characters of those great comprehensive tribes, on which it ceases to operate, because there is nothing left to oppress the memory, or the understanding. If there had been no such science as chemistry, who could have ventured to suppose, that the innumerable bodies, animate and inanimate, on the surface of our globe, and all, which we have been able to explore in the very depths of the earth itself, are reducible, and even in the imperfect state of the science, have been already reduced, to a few simple elements? The science of mind, as it is a science of analysis, I have more than once compared to _chemistry_, and pointed out to you, and illustrated, its various circumstances of resemblance. In this too, we may hope the analogy will hold,--that, as the innumerable aggregates, in the one science, have been reduced and simplified, the innumerable complex feelings in the other will admit of a corresponding reduction and simplification.