All my paintings start with a blue background: it represents the Mind in its unadulterated state. It also means that it is always attainable, permeating through, similar to my preferred message of hope: "the sky is always blue, even if clouds are temporarily in front".
The white gesso (a sort of layer for the actual paint) is the mind in its personable sense, it is one's mind, the substrate of thoughts. It gives movement and orientation to the whole painting, using the brush stokes to indicate this.
In some of my paintings, there is a blue line slashing through: the Mind is showing in a burst of light.