You mean before it was written down? Old recipes were transmitted orally from generation to generation and from master to apprentice. If you mean how the the re

You mean before it was written down? Old recipes were transmitted orally from generation to generation and from master to apprentice. If you mean how the the recipe was originally developed, this happened (and still happens) through trial and error. But if you know how the ingredients actually work and interact, you can experiment a lot safer. Of course trial and error is perfectly fine as long as you are prepared to accept "error" as a potential outcome.