The _second_ department of Nature's teaching, we have seen, consists in inducing and assisting her pupils to acquire knowledge.--This object we found her accomplishing by means of four distinct principles, which she brings into operation in regular order, according to the age and mental capacity of the pupil. These we have named the principle of "Perception and Reiteration," which is the same as that employed in her first process;--the principle which we have named "Individuation," which always precedes and prepares for the two following;--there is then the principle of "Association," or "Grouping," by which the imagination is cultivated, and the memory is assisted;--and there is, lastly, the principle of "Classification," or "Analysis," by which all knowledge when received is regularly classified according to its nature; by which means the memory is relieved, the whole is kept in due order, and remains constantly at the command of the will.--These four principles, so far as we have yet been able to investigate the processes of Nature, are the chief, if not the only, means which she employs in assisting and inducing the pupil to acquire knowledge; and which of course ought to be employed in a similar way, and in the same order, by the teacher in the management of his classes. The _third_, and by far the most important series of exercises in Nature's academy, we have ascertained, by extensive evidence, to be the training of her pupils to a constant practical application of their knowledge to the ordinary affairs of life.--These exercises she has separated into two distinct classes; the one connected with the physical and intellectual phenomena of our nature, and which is regulated by what we have termed the "animal, or common sense;" and the other connected with our moral nature, and regulated by our "moral sense," or conscience. In both of these departments, however, the methods which Nature employs in guiding to the practical application of the pupil's knowledge are precisely the same, consisting of a regular gradation of three distinct steps, or stages. These steps we have found to follow each other in the following order. There is always first, some fundamental truth, or idea--some definite part of our knowledge of which use is to be made;--there is next an inference, or lesson, drawn from that idea, or truth;--and there is, lastly, a practical application of that lesson, or inference, to the present circumstances of the individual. This part of Nature's educational process,--this application, or use of knowledge, we have ascertained and proved to be the great object which Nature designs by _all her previous efforts_. This part of her work, when completed, forms in fact the great Temple of Education,--all the others were but the scaffolding by which it was to be reared.--This is the end; those were but means employed for attaining it. In proof of this important fact we have seen, that when this object