The figure becomes the bond by which we compare and match objects that are different.
The figure that is developed through perception becomes the semantic feature or bond that is "drawn away" in the abstraction process. There are two types of bonds: Parts and Aspects.
Parts: A part is anything that can be physically dismantled (at least in your mind). A doorknob is a part, a feather is a part, appendages are parts, etc., etc., etc. Parts are widely used to categorize objects.
I actually had a near brush with failure because of my lack of attention to parts. As a senior Agricultural major at the University of Hawaii, I had to complete an entomology course to get my degree.
If I thought I was finished with using parts to learn categories in the elementary grades, I was sadly mistaken. In lab they handed us a book the size of Webster's Dictionary. It was full of insect parts which we had to be learned.