When chains of grey days crawl over the valley, grave and unrelenting, your eyes become empty and hungry. This is when you must forage and provide a feast.
Find a yew berry in an alley. You may have to kneel. Lean in. Let your vision be a giant sun of red. Your bloodstream may tingle, may even ache with consciousness after several minutes, but this is normal.
Find a yellow rose, in an arboretum or a warm shed with a window, however small. Bring your lashes to its petals, but do not blink. Your rods and cones will drink yellow, gulp it. They will become intoxicated. Yellow seeps down your spinal cord and you remember that you are a vertebrate, capable of passion and evolution.
Find a cobalt vase. It has been vacant for months. By now, you know what to do. Swim into the blue until you can close your eyes and still see blue, then swim deeper. Blue will unfold into your marrow, feeding the deepest recesses. Your cells are again prisms loaded with rainbows, stocked with nutrients of color.