to its true nature and its origin; that is to say, through its causes.
This method of cognition is the best if the true nature of a fact is to be learned. For if its true nature be not made evident, this is not cognition but error. The true nature of a fact lies in the process that brought it into being. If it appear to contain elements not accounted for by that process, it is evident that there is some misapprehension. Now everything is brought into existence by its causes. Therefore to explain the causes of anything is equivalent to making a true exposition of that thing’s nature, in accordance with the principles: “Knowledge consists in having a firm grip of causes,” and “Causes are the guides of the understanding.” Objects can thus be best, easiest, and most certainly cognised through a knowledge of the processes that produced them. If a man wish to read a letter he holds it as it was written, since it is a difficult thing to read a document that is inverted, or on its side, and in the same way, if a fact be explained by means of the process that gave it birth, it will be easily and surely understood. If, however, the teacher reverse the order of nature, he is certain to confuse the student. Therefore, the method employed in teaching should be based on the method of nature. That which precedes should be taken first, and that which follows last.
19. (v) If anything is to be learned, its general principles must first be explained. Its details may then be considered, and not till then.
The reasons for this have been given in chap. xvi. Principle 6. We give a general notion of an object when we explain it by means of its essential nature and its accidental qualities. The essential nature is unfolded by the questions what? of what kind? and why? Under the question what? are included the name, the genus, the function, and the end. Under the question of what kind? comes the form of the object, or the mode in which it is fitted to its end. Under the question why? the efficient
