same way the mind can only grasp one thing at a time. We should therefore make a distinct break in our progress from one thing to another, that we may not overburden the mind.
22. (viii) We should not leave any subject until it is thoroughly understood.
Nothing can be done in a moment. For every process involves motion, and motion implies successive stages. The pupil should therefore not pass on from any point in a science until he has thoroughly mastered it and is conscious that he has done so. The methods to be employed are emphatic teaching, examination, and iteration, until the desired result is attained. This we have pointed out in chap. xviii. Principle 10.
23. (ix) Stress should be laid on the differences which exist between things, in order that what knowledge of them is acquired may be clear and distinct.
Much meaning lies concealed in that celebrated saying: “He who distinguishes well is a good teacher.” For too many facts overwhelm a student, and too great a variety confuses him. Remedies must therefore be applied: in the first case order, by means of which one thing may be taken after another; in the second, a careful consideration of the differences that exist in nature, that it may always be evident in what respects one thing differs from another. This is the only method that can give distinct, clear, and certain knowledge; since the variety and actuality of natural objects depend on their distinctive attributes, as we have hinted in chap. xviii. Principle 6.
24. Now it is impossible that all teachers, when they enter on their profession, should be possessed of the requisite skill, and it is therefore necessary that the sciences which are taught in schools be mapped out in accordance with the foregoing laws. If this be done it will be difficult for any teacher to miss his mark. For, if the laws be rigorously observed, it is beyond question that any man who is once admitted into the royal palace and is allotted a certain space of time can easily and without any trouble
