other words to see how the memories that are registered in the brain act upon the outgoing pathways. We shall expect to find connecting nerve cells reaching across from the various arrival platforms to the motor area, and such connecting cells exist, but they are not simple and direct connections for a reason which we shall now try to make clear. We all know from our own experience that our memories are never the pure registering of a single sense. What we mean is that the sight of something by itself or the sound of something by itself never remains as a separate memory, but is always worked in with some other memories from some of the other sense organs. This putting together of the simple sensory memories began in earliest childhood, long before we were old enough to think about our mental processes, and see how they are carried on, so that unless our attention has been called to it, we have probably failed to realize how complicated our simplest memories are. A good example of this is in the experience of a baby with its mother’s voice. So far as the baby is concerned, the voice is an influence affecting the organ of hearing, arousing nervous disturbances which pass to the arrival platform for hearing in the brain and are registered there as memories, but it does not take the infant long to learn that some other memories that have come to it by way of other sense organs belong with this particular memory and always go with it. For example there is the sight of the mother, or the feel of the mother’s face and hands, all these are influences affecting different sense organs and registering in the child’s brain in different arrival platforms. Yet within his brain they become fused into a single composite memory of the mother, and after this fusion has once occurred, the arousing of any part of the memory brings up the whole of it, so that the child may hear the mother’s voice from the next room, but the memory that will be aroused as the result will be not simply of the voice but of the mother as a whole. This is an illustration of how our pure sense memories are fused into complex memories. After one of these memory complexes is once started, we add to it any time any sense organ is acted upon by anything that has relationship to the complex. For example, the child’s idea of the mother at first is a very simple one made up of a few sensory impressions, but as time goes on and more and more sensory impressions of the mother are received, the child’s idea of her becomes more and more complex. This process of memory fusion is called association or sometimes association of ideas. Strictly it is an association of memories and this is the method by which all our mental activities are carried on. The thought process consists of putting together various memories in various ways and so building up associations of different kinds. Of course adults of wide experience can form associations which