Prism

Recently I acquired a prism. It hangs now in my window, where it fulfills all the normal duties of a prism: it shines bright spots and rainbows on my walls, a wake-up light across my eyes every morning at nine.

That's the prism in daylight. But unlike other prisms, this one doesn't give up at nightfall: it refracts the streetlights across my night-black walls, a faded arc of shadowy pinpoint rainbows - a drifting constellation, rocking as the prism, like a pendulum, oscillates in the wind.