SEQUENCE OF EXERCISES 341
and only after they have for a long time eliminated every error in constructing the other two sets, do they succeed in arranging the Long Stair perfectly. This may then he considered as the most difficult among the series through which dimensions are taught.
Arrived at this point in his education, the child is capable of fixing his attention, with interest, upon the thermic and tactile stimuli.
The progression in the sense development is not, therefore, in actual practice identical with the theoretical progression which psychometry indicates in the study of its subjects. Nor does it follow the progression which physiology and anatomy indicate in the description of the relations of the sense organs.
In fact, the tactile sense is the primitive sense; the organ of touch is the most simple and the most widely diffused. But it is easy to explain how the most simple sensations, the least complex organs, are not the first through which to attract the attention in a didactic presentation of sense stimuli.
Therefore, when the education of the attention has been begun, we may present to the child the rough and smooth surfaces (following certain thermic exercises described elsewhere in the book).
These exercises, if presented at the proper time, interest the children immensely. It is to be remembered that these games are of the greatest importance in the method, because upon them, in union with the exercises for the movement of the hand, which we introduce later, we base the acquisition of writing.
Together with the two series of sense exercises described above, we may begin what we call the "pairing