Deeply then are laid the fountains of happiness in the constitution of human nature. They spring from the depths of man's physical organization; and from the wider range of his mental constitution they flow in streams magnificent and glorious. It is conceivable that from the first to the last moment of his existence, every human being might drink of them to the full extent of his capacity. Why does he not? The answer will be found in that to the following question. What must happen before this be possible? The attainment of clear and just conceptions on subjects, in relation to which the knowledge hitherto acquired by the most enlightened men is imperfect. Physical nature, every department of it, at least, which is capable of influencing human existence and human sensation; human nature, both the physical and the mental part of it; institutions so adapted to that nature as to be capable of securing to every individual, and to the whole community, the maximum of happiness with the minimum of suffering—this must be known. But knowledge of this kind is of slow growth. To expect the possession of it on the part of any man in such a stage of civilization as the present, is to suppose a phenomenon to which there is nothing analogous in the history of the human mind. The human mind is equally incapable of making a violent discovery in any department of knowledge, and of taking a violent bound in any path of improvement. What we call discoveries and improvements are clear, decided, but for the most part gentle, steps in advancement of the actual and immediately-preceding state of knowledge. The human mind unravels the great chain of knowledge, link by link; when it is no longer able to trace the connecting link, it is at a stand; the discoverer, in common with his contemporaries, seeing the last ascertained link, and from that led on by analogies which are not perceived by, or which do not impress, others, at length descries the next in succession; this brings into view new analogies, and so prepares the way for the discernment of another link; this again elicits other analogies which lead to the detection of other links, and so the chain is lengthened. And no link, once made out, is lost.