https://www.skillshare.com/classes/Watercolour-Rose-Using-lost-edges-to-create-form-and-depth/1059329951

Edges are an important element of a painting and being aware of how different edges can help to create depth and form in our paintings is an important skill to learn. Where you place your soft and lost edges and where you position your hard defined edges have a huge influence on where you direct the eye of your viewer.