But even this does not exhaust the catalogue of benefits to be derived from the use of the catechetical exercise in communicating knowledge to the young. We have supposed only one question to have been asked by the teacher upon the original sentence, and yet we have seen that this one question has in fact in a great measure secured the understanding of the whole of the ideas contained in it. But instead of one question, the catechetical exercise has the power of originating many, each producing successively similar results, but with greater ease to the child, and with much more effect in rivetting the several ideas upon the memory. The first question, when properly put, gives the pupil the command of the whole proposition; but it requires considerable mental effort in the child to recall the words, and internally to translate the ideas _for the first time_. But when this has once been done, and a second question is asked from the same sentence, the ideas being now more familiar, there is less mental labour required in preparing the answer, and there being equal success, there is of course more satisfaction. The ideas become much more clear and distinct before the mind by a second review; and the effect, in fixing the whole upon the memory, is much more powerful than it could be by means of the first. When therefore the teacher confines himself to the original sentence, and does not indulge in catechetical wanderings, the questions, "When did God make all things?" "How many things did God make?" "Of what did God make all things?" and, "Why did God make all things?" produce extensive and powerful effects. The pupil finds himself able to master each question in succession without difficulty, and the answering of each appears to him a triumph. Whoever has been in the habit of making use of this exercise in the manner explained above, must have witnessed with pleasure the life, and energy, and delight, which it invariably infuses into the scholar, giving education a perfectly different aspect from what it usually assumes in the eyes of the young, and making it even in the estimation of the pupil a formidable rival to his play. In this manner has Nature set her seal upon this exercise, as a near approximation to her own process for attaining the two preparatory objects she has in view in the education of the young; that of cultivating the powers of the mind, and that of communicating to her pupils the elements of knowledge. This exercise has been reduced to a regular system, which has placed it more directly at the command of all who undertake the instruction of the young. By a little attention on the part of parents and teachers, to a few simple rules, they may catechise upon any book, and apply the exercise to any species of knowledge whatever. We shall endeavour to explain the nature and uses of these rules.