Sory if I'm late on this...
I like Morgan's answer, that sounds very good to me as well as documented.
I just wanted to add that it's called "classical" since another "point of view" has been developped about composition.
This "modern" POV (as opposed to the "classical" one) considers that the human eye (and brain) is a "zoom lens" that one can "focus on any point one likes in the frame.
It applies to cinema vs photography, because the screen is supposed to be much wider than a photography, as well as the image is moving in time, what still picture is not.
Therefore there is a "dynamic" viewing, better than a static one.
It' based on the fact that there are three mental viewing angle possible.
The perception angle (about 180°) where you don't necessarly see but more likely "feel" the image ;
The observation angle, which likely 60°, in wich we see
The attention angle, that we use to examine details, that is around 1°
It also takes in account the fact that in really life everything seems to always be in focus, as an whole image.
Regards.