The scholars, therefore, should learn, and learn thoroughly, the etymology of all words, the reasons for all constructions, and the principles on which the rules for the various subjects of study have been formed (the principles of the sciences should in the first instance be impressed on the mind, not by merely giving the reasons, but by actual demonstration on the objects themselves).
This will prove most congenial to the pupils, and will therefore be of the greatest use in paving the way for the most thorough education possible; for their eyes will be opened to a remarkable extent, and they will acquire the habit of easily and naturally advancing from one thing to another.
37. In schools, therefore, everything should be taught through its causes.
Ninth Principle
38. Nature preserves a due proportion between the roots and the branches, with respect to both quality and quantity.
The development of the branches above the earth is proportionate to that of the roots beneath. This could not be otherwise; for if the tree were only to grow upwards it would be unable to maintain its erect position, since it is the roots that help it to do so. If, on the other hand, it only grew downwards it would be useless, for it is the branches and not the roots that bear the fruit. With animals also there is a close connection between the external and the internal organs, for if the internal organs are healthy the external ones are so also.
39. Imitation.—The same holds good of education. It must first be applied to the inner roots of knowledge, and thus develope and gain strength, while at the same time care must be taken that it afterwards spread out into branches and foliage. That is to say, whenever instruction is given the pupil should be taught to apply his knowledge practically, as in the case of a language by speaking, and not merely to assimilate it mentally.
