Fog's a species of weather-- gray, like a pigeon's feather. Auden once wrote, "Thank you, fog." Sandburg thought of cat, not dog. Fog's in Eliot's Unreal City-- yellow fog, what a pity. Call it mist, call it fog: Still you tripped over that log. If you can, take off work. No sense traveling in that murk. Anything you try to say will come out mumbled, foggy gray. The fog is subtler than the snow. And so it's the more dangerous foe.