ral
development.

This will give some idea of the difficulty of scientific researches,
which many still believe it possible to make by means of arbitrary and
superficial tests such as those of Binet and Simon!

* * * * *

The study of the child cannot be accomplished by an "instantaneous"
process; his characteristics can only be illustrated cinematographically.

"External means," organized in accordance with the needs of psychical
life, are of fundamental importance; for how is it possible to judge
of individual differences in the acquisition of internal order, in the
ascent to abstraction, in the progressive stages of intellectual
development, in the achievement of discipline, without the existence
of pre-determined and unvarying external means which, like so many
points of support, lead the child in process of formation towards his
goal?

In order to determine _individual differences_ logically, there must
be a _constant work or aim_; and this is the external means on which
each personality builds itself up. When the external support is the
same, and corresponds in general to the psychical needs of a given
age, a difference of internal construction is _due to the individual
himself_. On the other hand, if the means were different, the
variations in reaction might be attributed to differences in the
means.

Finally, it is obvious that in all scientific research, the
_instrument of measurement_ must be fixed. But each _thing to be
measured_ requires a special instrument, and the constant instrument
in psychical measurement should be "the method of education."

A series of formulae, such as the Binet-Simon tests, can neither
measure anything, nor give even an approximate idea of intellectual
levels of intelligence according to age; as to the children who
respond, whence is their response derived? How far is this due to the
intrinsic activity of the individual, and how far to the action of
environment? And if the portion due to environment be ignored, who can
determine what intrinsic psychical value should be given to the
response?

In each personality we must recognize two parts: one is the
individual, natural, spontaneous activity by means of which elements
may be taken from the environment wherewith the personality may be
elaborated internally, constructed and augmented, and hence
_characterized_; another part is the external instrument with which
all this may be done. For instance, a child