Note 67 — FREDERIC THE GREAT’S EULOGY ON JULIEN OFFRAY DE LA METTRIE. (continued 2)

I shall not go into any more detail concerning all these little subordinate forces, well known to all. But there is another more subtle and marvelous force, which animates them all; it is the source of all our feelings, of all our pleasures, of all our passions, and of all our thoughts: for the brain has its muscles for thinking, as the legs have muscles for walking.67 I wish to speak of this impetuous principle that Hippocrates calls ενορμων (soul). This principle exists and has its seat in the brain at the origin of the nerves, by which it exercises its control over all the rest of the body. By this fact is explained all that can be explained, even to the surprising effects of maladies of the imagination....