Confusion with Bi-directional Associations limitation

Hi,

I was reading this Bi-directional Associations topic in the guide - http://guides.rubyonrails.org/association_basics.html#bi-directional-associations. There I saw some limitations, they have mentioned. One limitation which I am not able to understand is :

  • for belongs_to associations has_many inverse associations are ignored.

Any light on this topic ?