The creation story in Genesis illustrates the power of a name to validate existence. God creates all the animals so that Adam will no longer be alone on Earth. At the end of the day, all the animals congregate in Eden to receive a name. Thus, the final act of creation comes from the power of language. Adam has been given a vocabulary to understand the world.
Diagnosis provides that vocabulary for patients.
Putting a name on a problem validates that something has gone wrong in their bodies. It can reassure them that someone else has experienced similar difficulties. They are no longer alone in their suffering. Barbara first saw a psychiatrist at the age of 10 and has been in and out of hospitals for the past 50 years. Yet, an accurate diagnosis was not forthcoming.