Why Does “Dream” = “Ideal”?

I’m always puzzled when people refer to their “dream girl,” or their “dream house,” when they’re talking about their ultimate ideal. Why is the word “dream” synonymous with “ideal”? My nighttime dreams never reflect what I really want. For example: 

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On my ideal date, a pretty lady laughs at my jokes over a delicious meal. We end the night by making passionate love.

On my dream date, my 7th grade science teacher points and laughs at my teeth as they slowly crumble into the gravy boat. Our sommelier, Nick Nolte, brings us a bottle of live ants.

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At my ideal job, I get paid ridiculous sums to write short, pithy articles for a famous magazine.

At my dream job, it’s 5 minutes before the big presentation and I still can’t get the photocopier to work. I have to share a cubicle with a black version of Nick Nolte, who won’t ever let me use the bathroom and makes me pee in Ziploc bags at my desk.

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On my ideal vacation, my family and I stroll through Central Park on a perfect autumn day. 

On my dream vacation, we get on the wrong plane which is not a plane but a giant dying tree and why is black Nick Nolte sitting on the branch next to me and I can’t see what’s happening but my children are in trouble and shit shit shit there go my teeth again.