Arch from the Outside

So Grosz's essay writes about the nature of space and time. I believe she is challenging my present understanding of both. In the past, I have seen space as a medium similar to water shaped by its container and architects as the shapers of space through the use of materials. However, Grosz speaks of the materiality of space itself not as a medium or a "passive receptacle" but as a "moment of becoming. . .a space of change, which changes with time." I am having some difficulty wrapping my mind around this. Any thoughts to elucidate?