When learning about people, either through biographic readings or in person, I'm very interested to learn which "object" has had the single greatest effect on them. For example, what has made an indelible mark that changed their life, or "altered the colour of [their] mind", or imputed unto them a goal or a passion they've been chasing ever since. I suppose a person can have more than one of these objects, but we usually have only one for any given context.
These type of objects are usually books or music albums, and I want to know which of them are esteemed in this way, because those are exactly the objects I want to add to my personal collection.
I liked "lodestar" for a bit, but it implies an everlasting guide that one can reliably call upon, or to extend the metaphor, implies something that one still necessarily believes in.