But please correct me if i'm wrong:
to better conceptualize all the different relationships, think of them as this:
has_one_in :your association
I may be wrong but I think you're thinking of the tables rather than the objects the tables represent.
Think of how you would describe the relationship between (using Gareth's example), a Millionaire and his Houses:
A millionaire has many houses
A house belongs to a millionaire
Does that make sense?