When a person is sent to learn an art or trade, such as a carpenter, he is not sent to hear lectures, or to get merely an abstract knowledge of the several truths connected with it; but he is sent to practise the little knowledge that he is able of himself to pick up. His is a practical learning; ninety-nine parts in every hundred being employed in the practice, for one that is employed in acquiring the abstract principles of his occupation. When, on the contrary, a child is sent to school, to prepare him for this practical application of his knowledge, the former proportions are generally reversed, and ninety-nine parts of his time and labour are taken up in attaining abstract knowledge, for one that is occupied in assisting him to reduce it to practice. Both modes of teaching the boy are obviously wrong. He would, when sent to it, learn his business in much less time by a previous acquaintance with its principles; and all these ought to have been furnished him as a part of his general knowledge while he attended the school. Such information, indeed, ought to have formed a large portion of his education;--and it will be a matter of surprise to every one who closely considers the subject, how soon and how easily the principles, even of so complicated a trade as a carpenter, may be acquired when they are taught in the right way, and at the proper time. A few of the simplest principles in mechanics practically learned,--a knowledge of the strength and adhesion of bodies,--of the nature of edge tools,--and the importance of accuracy and caution, might have been made familiar to him while attending his studies; and if carefully and constantly reduced to practice, these would have been of the greatest service to him when called to the work-shop. The methods by which natural philosophy ought to be taught in schools, must partake of all the laws which Nature employs in the several parts of her teaching. Individuation, Grouping, and especially Analysis, must be rigidly attended to. By dividing all the subjects of general knowledge into the two grand divisions of Terrestrial and Celestial, and these again into their several parts, the whole field of useful knowledge would be mapped out, and connected together, so that each subject would occupy a distinct place of its own, and be readily found when it was required. The facts, or at least the most useful facts connected with each of these, would very soon be communicated; and when turned into a popular and useful form, by drawing and applying the corresponding lessons, the ease and delight of laying up these precious stores of useful knowledge by children, will not be easily conceived by those who have not witnessed it.