I’m only going to mention this briefly because there is far more information available on this elsewhere on the web and written by far more lucid writers than myself. The three act structure, with its origins arguably found in theatre also resonates with the mythic story structure suggested by Joseph Campbell. Joseph Campbell, particularly in his book, The Hero With A Thousand Faces (no writer should be without this on their shelves) describes the stages of the journey that all characters from myth go through.
Check out the explanation given on Wikipedia, buy the book (no, I’m not getting a cut. Just buy it.) and see how our distant ancestors fully understood the key components of story thousands of years before Hollywood turned it into a formula.
