天文学者でありSF作家でもあった米国の Carl Sagan の言葉だということです。
> Enjoy your weekend with lots of good apple pie!
> If you wish to make an apple pie from scratch, you must first invent the Universe (CS).
What did Carl Sagan mean when he said "If you wish to make
apple pie from scratch, you must first create the universe"? - Quora
The word "scratch" in that sentence means the same as "zip",
"nada", "goose egg", etc. -- that is, "nothing".
So, if you make an apple pie using apples, flour, sugar, etc. that you
purchased at the store, you're not really making the pie "from scratch".
You must admit that the farmers that grew the apples, harvested the grain
and sugar cane, along with the truck drivers that delivered the goods to
the store, etc., all had a hand in making your pie.
But even if you grow the apples, wheat and sugar cane in your own
backyard, and grind the wheat to flour using tools you fashioned yourself,
and extract sugar from the cane yourself, you're still relying on many
things you did not make: the soil, the sunlight, etc.
The only way to really make an apple pie "from nothing", would be to
create the universe yourself.
That is what Carl Sagan meant.