“Elementary, my dear watson” is a sherlock holmes “quote”, which is sometimes used to roughly say “it is actually quite simple”. Take away the “my dear” and the post roughly sounds like the “quote”.

I can help.
When you look up and see an airplane, where is it going? The most accurate answer with the limited information you have is to an airport. You don’t know which city or which airport. But most probably to an airport.

Same with the with the lemon. You don’t know what country or grocery store. But lemons do come from trees.

Until we meet again…