" London fog’s fascinating. Just take its colours, for instance – it may be several all at once. In some parts it’s light grey, and you can still see things within a range of forty or fifty feet. In other parts, it’s such a dark grey that there’s no difference between night and day. In some places it’s greyish yellow, as if the whole of London city is burning damp wood. In yet other places, it’s a reddish brown, and when the fog is this colour you can forget about being able to see anything any more. All you can spot if you’re standing indoors, looking out the windowpane, is the reddish brown colour. If you walk in the fog, it’s dark grey just ahead of you, and it’s not until you raise your head and make an actual effort to pick out a lamp shining somewhere, that you can see the faintest yellow tinge to it. That sort of fog doesn’t come in wisps, but in one whole mass, and blocks out the world. As you walk, the fog follows you. You can’t see anything, and nobody can see you. You don’t even know where you are. Only the fiercest-burning gas lamps penetrate the gloom, and all you can distinguish are the wisps of steam from your own breath before your lips. The rest is hazy and unidentifiable. "

― Lao She , Mr Ma and Son