The human eye views shapes as abstractions, to which our minds give meaning. For example, if we look at three cubes, our mind says the largest one is closest to us. As artists we use tools such as size, placement, value and color like breadcrumbs, to help the viewer follow the trail as we lead through our painting. So if we want them to see a ball, we make a circle, to tell the viewer they are looking at a round shape. Then we darken and dull the edges where the light is further away than on the closest surface where it strikes more lightly and brightly.
The shape of something can also indicate a mood or feeling. WWI left much of Europe like Ukraine looks today – bombed, burned, devastated. Some artists responded by reviving historical art and themes, such as Picasso’s Three Women at the Spring. The figures are monumental shapes, classically styled, looking solid as the earth itself. Compare this to the tall, extremely thin people of Giacometti, created a few years later – perfect to express his concept of isolation, fear and anxiety caused by the uncertain times of the Cold War.
Think about the shapes you are using as you compose your painting. Whether figurative or abstract, the shapes you use can tell a story. Sharp edges and hard lines feel differently than softly rounded curved shapes. What story are you trying to tell, what world do you want your viewer to experience? Whether you liked his art or not, I think Bob Ross was onto something when he said we can create our art to express the shape of our world just as we want it to be.