counterpart in the brain there must be 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.