The eye altering, alters all. - William Blake
Making a formal psychological diagnosis can be a mixed blessing. It has several potential advantages. If many of my symptoms can be accurately grouped under a specific psychological diagnosis, it may well help to understand what is happening, to clarify the likely time course of my symptoms, and to choose treatments that have the best chance of being effective. It's worth noting that often people suffer from more than one psychological disorder at the same time - this is called comorbidity and it is common.