a relation sui generis, which is neither
the determination of the one by the other, nor their reciprocal
independence, nor the production of the latter by the former, nor of the
former by the latter, nor their simple parallel concomitance; in short,
a relation which answers to none of the ready-made concepts which
abstraction puts at our service, but which may be approximately
formulated in these terms: ("Report of the French Philosophical
Society", meeting, 2nd May 1901.)

"Given a psychological state, that part of the state which admits of
play, the part which would be translated by an attitude of the body
or by bodily actions, is represented in the brain; the remainder is
independent of it, and has no equivalent in the brain. So that to
one and the same state of the brain there may be many different
psychological states which correspond, though not all kinds of states.
They are psychological states which all have in common the same motor
scheme. Into one and the same frame many pictures may go, but not all
pictures. Let us take a lofty abstract philosophical thought. We do
not conceive it without adding to it an image representing it, which we
place beneath.

"We do not represent the image to ourselves, again, without supporting
it by a design which resumes its leading features. We do not imagine
this design itself without imagining and, in so doing, sketching certain
movements which would reproduce it. It is this sketch, and this sketch
only, which is represented in the brain. Frame the sketch, there is a
margin for the image. Frame the image again, there remains a margin, and
a still larger margin, for the thought. The thought is thus relatively
free and indeterminate in relation to the activity which conditions it
in the brain, for this activity expresses only the motive articulation
of the idea, and the articulation may be the same for ideas
absolutely different. And yet it is not complete liberty nor absolute
indetermination, since any kind of idea, taken at hazard, would not
present the articulation desired.

"In short, none of the simple concepts furnished us by philosophy could
express the relation we seek, but this relation appears with tolerable
clearness to result from experiment."

The same analysis of facts tells us how the planes of consciousness,
of which I spoke just now, are arranged, the law by which they are
distributed, and the meaning which attaches to their disposition. Let us
neglect the i