part movements which retrace its main lines, our memory directs upon the perception received the memory-images which resemble it and which are already sketched out by the movements themselves. Memory thus creates anew the present perception; or rather it doubles this perception by reflecting upon it either its own image or some other memory-image of the same kind. If the retained or remembered image will not cover all the details of the image that is being perceived, an appeal is made to the deeper and more distant regions of memory, until other details that are already known come to project themselves upon those details that remain unperceived. And the operation may go on indefinitely;—memory strengthening and enriching perception, which, in its turn becoming wider, draws into itself a growing number of complementary recollections. So let us no longer think of a mind which disposes of some fixed quantity of light, now diffusing it around, now concentrating it on a single point. Metaphor for metaphor, we would rather compare the elementary work of attention to that of the telegraph clerk who, on receipt of an important despatch, sends it back again, word for word, in order to check its accuracy.
But, to send a telegram, we must know how to use the machine. And, in the same way, in order to reflect upon a perception the image which we have received from it, we must be able to reproduce it, i.e. to reconstruct it by an effort of synthesis.
