Balance is one of the easier Elements of Composition to see, and you'll soon discover whether your natural inclination is towards a perfectly balanced or symmetrical composition or an unbalanced, asymmetrical one. It's not that one is better than the other, but whichever you choose as the underlying component of your composition has an impact on the overall feeling of the finished painting. Symmetrical tends to feel calmer and asymmetrical livelier.
I'm using the famous Mona Lisa painting to illustrate the role of balance in a painting, because while it is mostly a balanced composition, the positioning of the figure is slightly off-center, or off-balance.
The face in a portrait is typically the focal point, and this painting is no exception. We're seeing the face straight on, and there's balance created as we're seeing equal amounts of the face on either side of the nose. (If the face had been at an angle, we would see more of one side of the face than the other.) Yet if you draw a line down the center of the face, you'll notice it's not positioned in the center of the canvas, but a little way to the left. So the balance is undermined somewhat, though without careful looking it's hard to put your finger on exactly why. But the composition results in the face looming out of the painting towards the viewer, giving it more impact.
Take a look at the background, analyzing the dominant colors. You'll see it forms horizontal bands, which I've shown in red on the photo. The varying widths of these bands add visual interest to the composition, it's a change of rhythm, but it's gentle. A subtle effect of the diminishing width of the bands towards the top reinforces the effect of perspective on the background.
Now look at the bands in terms of the negative space around the head. How large is each, and is it equal on either side of the figure? For instance, in the negative space around her shoulders, there's more on the left-hand side than the right. What at first glance appears to be balanced, isn't totally.
Next page: Layers of Balance