Well it goes like this someone discoved fire and also that it was hot and taught others hey don't play with fire or you will get burned. No theory needed. Now when you want to know why something is hot you look at what makes it combustible and at what temp and what breaks down and so on and so forth. Still known things no theory interjected. But if you want to know things you do experiments and repeat them. Not go well I think this is how it works and if it doesn't gravity then.
