“156. Why is the sky blue? -A fair enough question, and one I have learned the answer to several times. Yet every time I try to explain it to someone or remember it to myself, it eludes me. Now I like to remember the question alone, as it reminds me that my mind is essentially a sieve, that I am mortal.

157. The part I do remember: that the blue of the sky depends on the darkness of empty space behind it. As one optics journal puts it, "The color of any planetary atmosphere viewed against the black of space and illuminated by a sunlike star will also be blue." In which case blue is something of an ecstatic accident produced by void and fire.”