单项选择题

Admit it: at some point in your life, you’ve been completely obsessed. Obsessed with a particular project perhaps, or a great author,or that hot senior who smiled at you once when you were a freshman. Obsession is common and typically harmless, often a powerful motivator and a source of artistic inspiration. Yet its extremes are also feared and criticized, because they form the foundation for obsessive-compulsive disorder (OCD), a disease that has apparently exploded in prevalence in recent decades. How exactly can we reconcile two conflicting notions of the same phenomenon
Perhaps we can’t--but we can gain some insight by taking a closer look at society’s complex history with obsession, Lennard J. Davis assumes in his new book. Since the 18th century our understanding of obsession has evolved from believing it to be an incurable "madness", thought to afflict a small number of people who were typically poor, to a potentially curable disease afflicting many, including the upper classes.
Mental illnesses such as OCD and depression (or at least the tendencies toward them)have practically become a hallmark of passion. This association could partially explain why such illnesses are now so commonly diagnosed, Davis maintains since 1970 diagnoses of OCD have increased at least 40-fold.
Davis’s book also provides biographies of famous artists and psychiatrists with obsessive tendencies. Those who have a purely scientific interest in OCD, however, may find themselves a little bored at times. However, Davis makes several interesting points. For one thing, he says, the difference between OCD and healthy obsession may simply be self- perception. People with OCD feel they are abnormal and wish they could change; obsessive people who do not have OCD--including people with "obsessive-compulsive personality", considered by psychiatrists to be normal--feel just fine.
Considering the close relation between OCD and "healthy obsessions" ,Davis argues that we tend to draw too strong a line between the healthy and the pathological (病态的). Many people have careers that require repetitive-almost obsessive—attention,and most of us take notice of warnings to take careful precautions in our daily routines to stay healthy and protect ourselves. "We suffer from many requirements of modern life that make us focus on one thing, or many single things," Davis writes. OCD, he explains, is simply a subcategory (子范畴) of what we all do every single day.
What may be the difference between obsessive people and people with OCD according to Davis