My recent library selection of landscape and garden reading was "10,000 Garden Questions" . This book has a list of questions answered by about 20 experts. It must be an older book as the copyright is 1944 through 1982, which is cool, because I like to read older text for contrast to current ideas.
In the section on planning the landscape, there was the question what are the principles to consider in the design of a garden? In this list they had enclosure as a design priciple, which intrigued me. The garden "room" concept is how this seems to be referenced now, and I have never understood how to embrace this (or in some cases the need to).
But in any landscape design book or photo layout in a magazine, enclosure is seen in the photo. Maybe it's the limitation of the photo field of view compared to what the human eye can see, or enclosure has been a critical design element (.. not priciple) planned from the start. A solid fence around the garden, tall hedges, or tall mixed border planting is a component of many of the great pics in magazine shots. It focuses the eye inside the garden on the plantings or towards some other anthropogenic object, but it appears to be deliberate. If the external garden view is great (not your neighbours car or pool), then keeping the eye in the garden seems to be a design objective.
I'm sure you already knew this though, but it was one of those now I get it moments that comes up that I had to ramble on about.