"The moment one tries to define what habit is, one is led to the fundamental properties of matter. The laws of Nature are nothing but the immutable habits which the different elementary sorts of matter follow in their actions and reactions upon one another." So writes William James early in the fourth chapter of Principles of Psychology. Is he, as may at first appear, playing a semantic game here? I think not. We say that the electrons of an atom have a "habit" of acting in various law-like ways in a sense somewhat stronger than metaphor. After all, on such a basis we can also say that our neurons have a habit of acting in certain ways. It is a fair guess that certain thought patterns correspond to pathways of electrocal charges through a possible line of our neurons, and that once these pathways have been oft followed, their continued use in the future becomes more likely. Such a conjecture would provide a physical basis for habits of thought. We might sa...