For the purposes of this exercise, the school books of the pupil are supposed to consist of sentences, each of the principal _words_ in which conveys some specific idea;--these again are combined into _clauses_, which also convey an idea;--and the combination of these clauses in a _sentence_, or _paragraph_, usually forms a complete truth. For example, the sentence, "God at first [made all things] of nothing [to shew his greatness,"] contains one great truth; but the sentence which conveys it, embodies at least two _clauses_, inclosed in brackets, while the whole is made up of _words_, each of which is the sign of an idea which may readily be separated from all the others. Now it is evident, that questions may be formed by the teacher relative to each of these three parts. He may ask a question, which shall require the _whole_ truth for the answer; or one which will be answered by a _clause_; or another which is answered by a _word_. In "revising," accordingly, where time is an object, the teacher confines himself to those general questions which bring out the _whole truth_ at once, as is exemplified in the Larger and Shorter Catechisms. This is called the "Connecting Exercise," because it is employed in uniting sections together, which have previously been taught to the pupils separately, but which are necessary to be perceived also in connection. This, however, would be too limited an exercise for the purpose of directing the mind to the several parts of a truth for the first time; and therefore the teacher in those cases forms his questions chiefly upon the _clauses_ in the sentence, and the other words which have some material relation to them, and this is called the "General Exercise." But even this is not enough, where the child is dull, or where healthful mental exercise is required; and accordingly in that case, the teacher not only questions upon the clauses in connection with the other principal words, but he takes the _words_, of which the clauses are composed, and catechises the child upon them also. This is called the "Verbal Exercise," which has been found of great value in the teacher's intercourse with his younger classes. Upon these principles the Initiatory Catechisms and their Keys have been formed, together with the several Helps for communicating Scriptural knowledge. The success of these school books, although labouring under all the disadvantages of new instruments, imperfectly formed to work out new principles, is mainly to be attributed to the close imitation of Nature aimed at in all their exercises. The _rule_ for the parent or teacher in mastering these exercises is the same in all; it consists simply in forming the question in such a manner, as that the word, the clause, or the whole proposition, shall be required to make the answer. Sufficient explanation and examples of all this will be found in the Note.[13]