The instances of sympathetic magic as Dr. Hirn points out are naturally divided into two main classes which, broadly speaking, correspond to the two types of association, contiguity and similarity, and as in psychology it is often difficult to decide whether a given associative process has its origin in a relation of contiguity or in one of similarity, so it is often an open question to which group a given superstition is to be assigned. We will start from the facts that are simpler and easier to explain.
