Theatre-makers can take all manner of approaches to reality. Some, like the classical Realists, take it as read and seek to reproduce it. Others, like the Symbolists, understand it as a veil that hides a different set of truths. Brecht, as a practitioner profoundly influenced by his readings of Marx from the mid-1920s onwards, took a different stance.
For him reality was being continually created from the contradictions that pervade any given society at any given time. That is, society was unstable, volatile and unpredictable; its contradictions meant that things could change and forge new realities. Consider:
Yet change can also occur on a far smaller scale, too:
In each example, reality is remade after a material experience.
If reality is malleable, then change is always possible. Brecht sought to demonstrate this principle in his theatre practice.