Monet painted the cathedral over 30 times, and in doing so, shows us that even the most permanent, imposing of structures is breathtakingly mutable, contingent on changes in light, air, and time. He doesn’t paint the object, so much as the sensations aroused by a particular memory of it. His subject is not the cathedral, but everything else: the music of the colours bleeding into one another, the breath of the liquid air, the weird tactility of something both there and not. Most of all, it’s about time: as an irresistible force and common adversary to us all. As Marx said, “time flies like an arrow; fruit flies like a banana”.