What are the motifs in The Man Who Mistook His Wife for a Hat and Other Clinical Tales by Oliver Sacks?

A recurring idea that emerges is the possibility that Sacks' patients are not truly "sick." Often the reader gets the impression that the so-called "affliction" from which the patient suffers has actually enhanced the person's life. Quite possibly the disease enables the patient to live a fuller life and do things he or she may not have done otherwise.