I think you have a passion and an obsession for something when it's not necessarily ubiquitous.
“I have a good memory for early life. My visual memory is good about childhood and adolescence, and less good in the last 10 years. I could probably tell you less what happened in the last 10 years. I remember what houses looked like, sometimes they just pop into my head.”
“When you get something for nothing, you just haven't been billed for it yet.”