of simple impulses affecting them all alike.  I am happy to say that I never had an opportunity of observing the effect of complex impulses such as those of panic terror.  I used particularly to watch, from the vantage point of a stairway whence I could look over their heads, the behavior of the crowd standing in the cabin just before the boat made its landing.  Each person in the crowd stood still quietly, and the tendency was toward a loose formation to ensure comfort and some freedom of movement.  At the same time each was ready and anxious to move forward as soon as the landing should be made.  Only those in front could see the bow of the ferryboat; the others could see nothing but the persons directly in front of them.  When those in the front rank saw that the landing was very near they began to move forward; those just behind followed suit and so on to the rear.  The result was that I saw a wave of compression, of the same sort as a sound-wave in air, move through the throng.  The individual motions were forward but the wave moved backward.  No better example of a wave of this kind could be devised.  Now the actions and reactions between the air-particles in a sound wave are purely mechanical.  Not so here.  There was neither pushing nor pulling of the ordinary kind.  Each person moved forward because his mind was fixed on moving forward at the earliest opportunity, and because the forward movement of those just in front showed him that now was the time and the opportunity.  The physical link, if there was one, properly speaking, between one movement and another was something like this:  A wave of light, reflected from the body of the man in front, entered the eye of the man just behind, where it was transformed into a nerve impulse that readied the brain through the optic nerve.  Here it underwent complicated transformations and reactions whose nature we can but surmise, until it left the brain as a motor impulse and caused the leg muscles to contract, moving their owner forward.  All this may or may not have taken place within the sphere of consciousness; in the most cases it had happened so often that it had been relegated to that of unconscious cerebration.

I have entered into so much detail because I want to make it clear that a connection may be established between members of a group, even so casual a group as that of persons who happen to cross on the same ferry boat, that is so real and compelling, that its results simulate those of physical forces.  In thin case the results were dependent on the existence in the crowd of one common bond of interest.  They all wanted to leave the ferry boat as soon as possible, and by its bow.  If some of them had wanted to stay on the boat and go back with it, or if it had been a river steamboat where landings were made from several gangways in different parts of the boat the simple wave of compression that I saw would not have been set up.  In like manner the ordinary influences that act on men’s minds tend in all sorts of directions and their results are not easily traced.  Occasionally, however, there occurs some event so great that it turns us all in the same direction and establishes a common network of psychical connections.  Such an event fosters community education.