In a week of walking through Strasbourg, and staying in an apartment barely more than around the corner from the Cathedral, I found myself seeing it, and snapping pictures of it, in varying light and times of day.
It only took a couple of days for it to dawn on me that I was inadvertently experiencing what Monet set out to show when he painted his long series of paintings of the facade of Rouen Cathedral: the endless ways in which light, color and form play together and transform what we see.