There's your problem, you got overly specific. When you're formulating a search, you want to balance how many hits you get - the broader your formulation, the more likely the hits will include your target (if it exists) but the more hits you'll return.

In this case, my reasoning would go something like this, laid out explicitly: '"Wittgenstein" is almost guaranteed to be on the same page as any instance of this quote, since the quote is about Wittgenstein; LW, however, doesn't discuss Wittgenstein very much, so there won't be many hits in the first place; to find this quote, I only need to narrow down those hits a little, and after "Wittgenstein", the most fundamental core word to this quote is "Earth" or "sun", so I'll toss one of them in and... ah, there's the quote.'

If I were searching the general Internet, my reasoning would go more like "'Wittgenstein' will be on like a million websites; I need to narrow that down a lot more to hope to find it; so maybe 'Wittgenstein' and 'Earth' and 'Sun'... nope nothing on the first page, toss in 'goes around' OR 'go around', ah there it is!"

(Actually, for the general Internet, just 'Wittgenstein earth sun' turns up a first page mostly about this quote, several of which include all the details one could need aside from Dawkins's truncated version.)