Any passion can become an addiction; but then how to distinguish between the two? The central question is: who’s in charge, the individual or their behaviour? It’s possible to rule a passion, but an obsessive passion that a person is unable to rule is an addiction. And the addiction is the repeated behaviour that a person keeps engaging in, even though he knows it harms himself or others. How it looks externally is irrelevant. The key issue is a person’s internal relationship to the passion and its related behaviours.
