1) To show differences when compared: siblings who contrast sharply in interests and abilities; a color that contrasted clearly with the dark background.I mean, really. Just Ellis' title is perfect: London will fucking twat you in a minute, son.
2) To evince a difference that can distinguish meaning: Voiced and voiceless stops contrast in English but not in Cree.
3) The reactions of Americans and British to terrorism.
To my American readers - you know all those cliches about the British being unmoved by bombings? They're actually true, and they make you look like a bunch of wailing ninnies. Obviously, the scale of the London bombings pales compared to September 2001, but 9/11 itself pales in comparison to what London has endured before.
Maybe Americans might actually learn some British courage - and learn to deal with terrorism the only way you can: by staying free, and going on with your life while pursuing the criminals with law enforcement, not needless war. But I doubt it - as close as they are, the Tommies are still too foreign for the Yanks. Hell, we Canucks are too foreign for most Americans.
One other note about London, though - it would be the coolest thing ever if "Red" Ken Livingstone replaced Rudy "Prostate" Giuliani as "Most Revered Mayor."