The study of Mozart's letters and biography leads us to reconsider the psychiatric disorders from which he suffered. Indeed, it seems that Mozart demonstrated depressive episodes, some of which were severe and corresponded to the criteria of the DSM-IV classification. However, the arguments put forward by other authors supporting the occurrence of manic or hypomanic episodes (thus constituting a bipolar disorder diagnosis) are not supported by sufficient historic proof. Indeed, the length of time that the behaviors suggesting manic symptoms lasted is not compatible with such a diagnosis. Rather, Mozart's mood swings and impulsive behavior correspond to some traits of a personality disorder, that is, for the most part, symptoms of the dependent personality disorder. Evidence for this diagnosis appears most notably in Mozart's reactions to his wife's absences, but also in occasional behaviors as well as mood lability. The divergences in the classification of Mozart's symptoms, either into the field of bipolar disorders or into that of personality disorders, are closely linked to the nosological uncertainties that are still a source of debate in today's psychiatric research. We discuss a means of overcoming this limitation by considering the concept of "soft bipolar spectrum," a conceptualization that corresponds to Mozart's psychiatric history.