In Jan van Goyen's 1653 "View of the Rhine" (where he made a sketching trip in 1650-51), the lowering, brownish-gray sky takes up about 60% of the picture.
The curtainless windows were rectangles of electric-blue sky that turned to gray and then normal daylight as the patients rose and slowly, in their thin striped cotton robes, began wandering down the corridor that led into the common room.