_Possibility of such a Science._--The possibility of the science of the human mind has been denied by some; but without good reason. If we can observe and classify the phenomena of nature, in her varied forms, animate and inanimate, and ascertain in this way the laws to which she is subject; if it is possible thus to construct a science of plants, of animals, of the elements that compose the substance of the earth, of the strata that lie arranged beneath its surface, of the forces and agencies that at any time, recent or remote, have been at work to produce the changes which have taken place upon and within our globe--nay, more, if leaving our own planet we may, by careful observation of the heavenly bodies, learn their places, movements, distances, estimate their magnitude and density, measure their speed, and thus construct a science of the stars, surely the phenomena of our own minds, the data of our own consciousness, must be at least equally within our reach, and equally capable of observation, classification, and scientific statement. If we can observe the habits of animals and plants, we can observe also the habits of men, and the phenomena of human thought and passion. If the careful induction of general truths and principles from observed facts form the basis and method of true science in the one case, so in the other. _Science of Matter and of Mind analogous._--The science of matter, and the science of mind agree perfectly in this, that all we know of either is simply the phenomena which they exhibit. We know not matter as it is in itself, but only as it affects our senses. We perceive certain qualities or properties of it, and these we embody in our definition, and beyond these we say nothing, because we know nothing. Equally relative is our knowledge of mind. What it is in itself we know not, but only its phenomena as presented to our observation and consciousness. It thinks and feels, it perceives, remembers, reasons, it loves, hates, desires, determines; these exercises are matter of experience and observation; they constitute our knowledge and our definition of mind, and beyond we cannot go. _Modes and Sources of Information the same in both._--This being the case, it is evident that both our sources of information, and our mode of investigation, must be essentially the same in the two departments of science. In either case our knowledge must be limited to phenomena merely, and these must be learned by observation and experience. A careful induction of particulars will place us in possession of general principles, or laws, and these, correctly ascertained and stated, will constitute our science, whether of matter or mind.