Can you summon a song in your head? A melody?
It's that.. But it's your voice. And you employ it to think. It's how I argue with myself and reason my way through a thing. I'm not sure how I'd get along without it, except every once in a while I get stuck on a problem, so I do something different. Often, the right solution to the thing I wanted to do will pop into my head. Then I need to work backwards how I got there. Both are useful, I prefer the information up front though.
You might check out recipes for Indian lemon pickle. It's a way of salt fermenting them that results in a spicy delicious condiment that can last for ages.