One of the more neglected aspects of conditioned responding concerns its structure and its function, and this can be divided into two more or less specific questions. The first question asks about the origins of the behavior which is established as a result of conditioning: that is, what are the rules by which learning is transformed into the behavior we observe in the conditioning situation? The second question concerns the biological function of conditioning. Given that conditioning is so pervasive as a learning phenomenon, what is its function from a biological point of view and what advantages does it bestow on an animal? We will deal with the latter of these two questions in the next chapter, but for the moment let us consider the questions surrounding the origins of conditioned behavior.