THE process by which we connect what we call the objects of our senses, and also our ideas, into certain aggregates called classes, is of too much importance not to have attracted the attention of those who have engaged in the study of mind. Yet it is doubtful, whether metaphysicians have regarded CLASSIFICATION as an original power of the mind, or have allowed that what is included under that name might be resolved into simpler elements. The term Abstraction, I think, they have generally taken as the name of a distinct, and original, power, not susceptible of further analysis. But, in doing so, it seems (for the language of writers {248} is too loose on this subject, to allow us the use of more affirmative terms), they have restricted the name to the power of forming such ideas as are represented by the terms, hardness, softness, length, breadth, space, and so on. And this operation they rather consider as subservient to classification, than as that operation itself. The process, however, of grouping individuals into classes, has been regarded as sufficiently mysterious. The nature of it has been the object of deep curiosity; and the erroneous opinions which were entertained of it bewildered, for many ages, the most eminent philosophers; and enfeebled the human mind. What (it was inquired) is that which is really done by the mind, when it forms individuals into classes; separates such and such things from others, and regards them, under a certain idea of unity, as some thing by themselves? Why is the segregation thought of? And for what end is it made? These questions all received answers; but it was many ages before they received an answer approaching the truth; and it is only necessary to read with care the writings of Plato and of Aristotle, and of all philosophers, with very few exceptions, from theirs to the present time, to see, that a misunderstanding of the nature of General Terms is that which chiefly perplexed them in their inquiries, and involved them in a confusion, which was inextricable, so long as those terms were unexplained.