Bateson 101: when considering the material universe, "we shall commonly be able to say that the 'cause' of an event is some force or impact exerted upon some part of the material system by some one other part"
However, "in the world of ideas, it takes a relationship, either between two parts or between a part at time 1 and the same part at time 2, to activate some third component which we may call the receiver. What the receiver (e.g., a sensory end organ) responds to is a difference or a change"