Why do people behave as they do?The traditional answer is that they are located in a world of nonphysical dimensions called the mind and that they are mental.If we are asked why we have spoken sharply to a friend, we may reply, "Because I felt angry." It is true that we felt angry before, or as, we spoke, and so we take our anger to be the cause of our remark. We often feel hungry when we eat and hence conclude that we eat because we feel hungry. We seem to be saying, "When I have felt like this before, I have behaved in such and such a way."We tend to say, often rashly, that if one thing follows another, it was probably caused by it-- following the ancient principle of post hoc, ergo propter hoc (after this, therefore because of this).But how did the physical act of deprivation lead to the feeling of hunger, and how did the feeling move the muscles involved in ingestion?The person with whom we are most familiar is ourself; many of the things we observe just before we behave occur within our body, and it is easy to take them as the causes of our behavior.Feelings occur at just the right time to serve as causes of behavior, and they have been cited as such for centuries.It was probably first a practical question: How could a person anticipate and hence prepare for what another person would do?Of what stuff are they made?