the teacher, may be often the struggle of the understanding starting from that to which it is not by nature adapted, and travelling in search of something on which it may fix with greater satisfaction.  For, without supposing each man particularly marked out by his genius for particular performances, it may be easily conceived, that when a numerous class of boys is confined indiscriminately to the same forms of composition, the repetition of the same words, or the explication of the same sentiments, the employment must, either by nature or accident, be less suitable to some than others; that the ideas to be contemplated may be too difficult for the apprehension of one, and too obvious for that of another:  they may be such as some understandings cannot reach, though others look down upon them, as below their regard.  Every mind, in its progress through the different stages of scholastick learning, must be often in one of these conditions; must either flag with the labour, or grow wanton with the facility of the work assigned; and in either state it naturally turns aside from the track before it.  Weariness looks out for relief, and leisure for employment, and, surely, it is rational to indulge the wanderings of both.  For the faculties which are too lightly burdened with the business of the day, may, with great propriety, add to it some other inquiry; and he that finds himself overwearied by a task, which, perhaps, with all his efforts, he is not able to perform, is undoubtedly to be justified in addicting himself rather to easier studies, and endeavouring to quit that which is above his attainment, for that which nature has not made him incapable of pursuing with advantage.

That, therefore, this roving curiosity may not be unsatisfied, it seems necessary to scatter in its way such allurements as may withhold it from an useless and unbounded dissipation; such as may regulate it without violence, and direct it without restraint; such as may suit every inclination, and fit every capacity; may employ the stronger genius, by operations of reason, and engage the less active or forcible mind, by supplying it with easy knowledge, and obviating that despondence, which quickly prevails, when nothing appeals but a succession of difficulties, and one labour only ceases that another may be imposed.

A book, intended thus to correspond with all dispositions, and afford entertainment for minds of different powers, is necessarily to contain treatises on different subjects.  As it is designed for schools, though for the higher classes, it is confined wholly to such parts of knowledge as young minds may comprehend; and, as it is drawn up for readers yet unexperienced in life, and unable to distinguish the useful from the ostentatious or unnecessary parts of science, it is requisite that a very nice distinction should be made, that nothing unprofitable should be admitted for the sake of pleasure, nor any arts of attraction neglected, that might fix the attention upon more important studies.