The first thing that comes to mind is that we are usually landscaping in and around at least some existing elements. Not the least of which is usually a building. Things like patios, pergolas, pools, and gardens often are fitted in response to building shape at least in an abstract way.

The next thing that comes to mind is planting beds. Some people, as often evidenced by pictures posted here (see "save my marriage")will make beds and then fill them in with plants that fit into that form. Others will start with the placing the plants and allow the bed shape to take shape based on the form created by the plants.

I think that different people will see one as the form and one as the receiving form while another would see it as the opposite. Or perhaps, one would conciously choose to use which is which for situational reasons or just on a whim.

Which element is the form or the recieving form would be relative to the observer, much like a Chinese Ying and Yang symbol.

What prompted the posting, was a fascination with how seemingly opposite forms or structures could provide balance and unity in a design across a space, especially when viewed from above. The puzzle analogy seemed fitting. Two puzzle peices could be separated, but one could unconsciously unit the across a space.

Geometric structures or bed shapes can have a recieving form across a negative space to provide unity and balance what otherwise may be disparate shapes strewn about layout.

Maybe over-analyzing something really intuitive to everyone, but it shows how all lines or forms must have some purpose or seem out of place.

"Maybe over-analyzing something really intuitive to everyone, but it shows how all lines or forms must have some purpose or seem out of place."

It is always good to understand the actual reasoning that goes behind what a lot of us think is intuitive. Sometimes people want to believe that their intuition is an artistic gift because they do not understant the subconscious reasoning that is playing out in the back of their brains. It seems that a lot of people are much more content with being gifted as an artist than they would be in being intelligent enough to reason things out.

This form and receiving form unity and balance which you are talking about also points out that when something seems out of place, one way that it can be mitigated is by creating context by using this phenomena.