Will the real quotation please stand up?
I kind of agree with Lush’s Point 1 – don’t use google for your problem. Or at least: look up “literature search engine” or “quotation search engine” or a variation on that theme. Or try with this which was in the blue recently. I don’t know if it will be successful. I get a result like this sometimes and I simply read down the page looking for the most credible ‘looking’ site. If you are really asking about honing your google skills, there’s advanced search/explanations about best search methods at their site.
“I do not want to use a popularity contest to determine which version, if any, is the veridical quotation, so simply comparing Google scores is out.” Yeah, but that’s the problem — Google’s PageRank algorithm basically amounts to a popularity contest. Essentially, you’re using the wrong engine. Try things like WikiQuote, or search for authoritative sources like Bartlett’s, etc.
