Pierre Janet, once an important French psychiater, has created during his long and productive life an enormous 'oeuvre', inspired by an original vision on behavior. His works are not well-known, but in France the interest is growing, as shown by the reedition of soms of his books and the foundation of the 'Société Pierre Janet' in Paris. His approach of behavior is an important contribution to the theory of behavior and can be neglected no longer. In connection with these facts a review seems necessary.