Skill in systematic thinking the pupil will obtain through the solution of assigned tasks, his own independent attempts, and their correction. For such work will show whether he has fully grasped the general principles, and whether he is able to recognize them in and apply them to particulars. 70. These remarks on the initial analysis and the subsequent gradual uniting of the matter taught, hold true, in general and in detail, of the most diverse objects and branches of instruction. Much remains to be added, however, to define with precision the application of these principles to a given subject and to the age of the pupil. It will suffice, for the present, if we remind ourselves that instruction provides a portion of the occupations necessary to government (56). Now, instruction produces fatigue in proportion to its duration; more or less, of course, according to individual differences. But the more fatiguing it is, the less it accomplishes as employment. This fact alone shows clearly the necessity of intermissions and change of work. If the pupil has become actually tired, that is, has not lost merely inclination to work, this feeling must be allowed, as far as is practicable, to pass away, at any rate to diminish, before the same subject is resumed in a somewhat modified form. In order to have time enough for this, the systematic presentation must in many cases be postponed until long after the first lessons in the elements have begun, and conversely, the rudiments of a subject frequently have to be at least touched upon long before connected instruction can be thought of. Many a principle needs to be approached from a great distance.