There exists a science called Forensic Writing Analysis. This is used in the study of ancient texts of all types and in crime cases in court. It did not exist in the first 19 centuries  you reference. When Scripture analysis began Pius XII said the RCC should enter these studies as well, and scholars did. Therefore they too have identified the Q writings and also now know Paul was not author of all originally ascribed to him. 
Theories in science work are complex explanations for certain phenomena. They are VITAL to the subject. They do not grow up to be come facts or laws. A fact is a brief statement not a lengthy explanation, often an equation.
The suggestion of a modern course is wise for info needed today regarding ancient writings needs modern research to clearly explain ideas of the past not clarified ever before. 
I am posting this for readers interested in how this work is done.