A great quote from Edmund Burke (1729-1797) has been posted here by Kirk Wellum. Reading this quote led me to think of that other famous quote often attributed to Burke, which runs something like this: “All that is necessary for the triumph of evil is that good men do nothing.” I say “something like” because it turns out there are dozens of variants of this quote!
For a thoughful study of these variants, see Martin Porter, “ ‘All that is necessary for the triumph of evil is that good men do nothing’ (or words to that effect): A study of a Web quotation” (January 2002; http://www.tartarus.org/~martin/essays/burkequote.html). Porter actually concludes after an exhaustive study that Burke never said this second quote about the triumph of evil and good men doing nought! In this essay and a follow-up one (“Four Principles of Quotation: Being a follow up to A study of a Web quotation” (March 2002; http://www.tartarus.org/~martin/essays/burkequote2.html), Porter rightly argues that for a quote to be used correctly it must be cited exactly from the source and something of the context knowable.
He therefore gives four principles regarding making quotations—this is a must for students of history and those aspiring to be historians.
Principle 1 (for readers): Whenever you see a quotation given with an author but no source assume that it is probably bogus.
Principle 2 (for readers): Whenever you see a quotation given with a full source assume that it is probably being misused, unless you find good evidence that the quoter has read it in the source.
Principle 3 (for quoters): Whenever you make a quotation, give the exact source.
Principle 4 (for quoters): Only quote from works that you have read.
PS I would wholeheartedly affirm Principles 1 and 3. Principle 2 seems to engender too much skepticism. And Principle 4 seems to be a little narrow.