Boundary : "a line which marks the limits of an area; a dividing line."
When you look at a landscape there are no edges - the world continues to both sides of the view, as well as up and down. But as a painter you have to fit your subject into a finite space ( unless it's a commission for a very, very large wall! ).
Your canvas, board or paper will have four sides. You can choose the shape and size, but ultimately, your painting has to end at some point.
When I'm painting a watercolour I often just start with my focal point and paint my way out ... sometimes at the end I might crop the paper to frame a pleasing part of what I've painted. That way of working makes me happy.
When I'm painting an acrylic it's a different kettle of fish (now there's a nice title for a painting) as I'm limited by the shape and size of my board or canvas. Too often I try to squeeze things in, or stretch them to fill the space! The edges sometimes confine me and dictate what I'm going to paint, a feeling which I don't always like.
So today I decided to deliberately work on a board bigger than my subject and just see how much space it wanted to fill. First I sketched in the view that interested me (The Travers River at the far end of our lake) then I masked off the right space to complete the painting. Once it's done I'll get my long suffering Man to trim the board down ready to frame. Sometimes he says to me wistfully "Why don't you just make all of your paintings a standard size?"
"Travers Valley " - acrylic on board 280 x 360mm (eventually)