THE MATERIAL FOR DEVELOPMENT 145
taken as the reason of the importance given to it in our Method,
while the second to us is not less, but actually its prime motive.
Our experience and that of our followers has only served to
strengthen our idea.
We may, in conclusion, mention the great service rendered by
our sensorial apparatus and the exercises done with it, for the
detection of defects in the functions of the senses at a period when
much can yet be done towards remedying them.
GENERAL REFERENCE TO THE MATERIAL FOR THE
EDUCATION OF THE SENSES
Material for training the senses comprises a system of objects
which are grouped together according to some definite quality
which they possess, such as colour, shape, dimension, sound,
surface texture, weight, temperature, etc. Examples of these are: A
set of bells which reproduce musical tones; a collection of tablets
which present different colours in a graduated scale; a group of
solids which have the same shape but graduated dimensions and
others which differ among themselves in geometrical form; things
of different weight but of the same size, etc., etc.
Objects of every single group represent the same quality but
in different degree; it is then a question of gradation in which the
difference between object and object varies regularly, and is when
possible fixed mathematically.
Such general rules are, however, subject to a practical con-
sideration which depends on the mentality of the child; and as
being suitable for education there will be chosen, as the result of
experience, only material which effectively interests the little child
and attracts him into doing voluntarily and repeatedly an exercise
- chosen by himself.
Every group of objects (material for sounds, material for
colours, etc.) which presents a gradation has therefore its extremes*
the maximum and minimum of the series, which determine the
limits of it and which, more correctly, are fixed by the use which