When you look into the cloudless sky, it has the appearance of being empty. Of there being nothing there. Of being just one unmodulated sameness. But to the bird that flies in it, it is not. The bird is sensitive to all the eddies and currents and all of the contours and nuances of the empty space that you can’t see. The bird picks them all up. The bird can sense an impending change in weather from afar.