The accuracy of this analogy, we think, will readily be admitted by all. And if so, it will at least help to illustrate, if it does not prove, some of the important conclusions to which we shall find ourselves led upon other, and philosophical grounds. But as the prejudices which, during several centuries, have been gradually congregating around the science of education are so many and so powerful, every legitimate means, and this among others, should be combined for the purpose of removing them. CHAP. III. _How Nature may be imitated in Communicating Knowledge to the Pupil, by the Reiteration of Ideas._ The phenomenon in mechanics and natural philosophy, which is popularly termed "Suction," may be exhibited in a thousand different ways, and yet all are the result of but one cause. When we witness the various phenomena of the air and common pump,--the barometer and the cupping glass,--the sipping of our tea, and the traversing of an insect on the mirror or the roof,--the operations appear so very dissimilar, that we are ready to attribute them to the action of a variety of agents. But it is not so;--for when we trace each of them back to its primitive cause, we find that each and all of these wonders are produced by the weight of the atmosphere, and _that alone_. In precisely the same manner, knowledge may apparently be communicated to the human mind in a thousand different ways; and yet, when we examine each, and trace it to its primitive cause, we find the phenomenon to be one--and _one alone_. The truth has been received and lodged with the memory,--made part of our knowledge--by _the reiteration of its idea_ by the mind itself;--by an exercise of active, voluntary thought upon the knowledge thus communicated. The cause and the effect invariably follow each other both in old and young; for whenever a new idea is perceived and reiterated by the pupil,--if it should be but once,--the knowledge of the child is to that extent increased; but whenever this act of the mind is awanting, there can be no additional information received;--the increase of knowledge is found to be impossible. This appears to be a law of our Nature, to which we know of no exception.