The term “gray” evolved for magic that could be classified as neither white nor black. Minor revenge would be considered a type of gray magic.

"I BlackBerried a sort of risque joke message to this friend of mine — it was totally a joke — but, um, I accidentally sent it to two hundred strangers. […]

A field is clearly a simple ring. Indeed, a commutative simple ring with unity must be a field (Problem 1, Section 1). An example of a noncommutative simple ring is Fₙ, the n × n matrix ring over a field F, n > 1.

Plainly it was not the custom for a foreigner to travel down the Yangtze on a small boat, for no sooner was I nicely settled on the deck of a tug about to leave for Anking, ninety miles down the river, than a boatload of Chinese river police pulled alongside and requested to see my passport.