This is very difficult, but the propagandist is no longer content to have obtained, or to believe he has obtained, a certain result; he seeks precise evidence. Even successful political results do not completely satisfy him. He wants to understand the how and why of them and measure their exact effect. He is prompted by a certain spirit of experimentation and a desire to ponder results. From this point on, one can see the beginning of scientific method. Admittedly, it is not yet very widespread, and those who analyse results are not active propagandists but philosophers. – Propaganda: The Formation of men’s attitudes, Jacques Ellul.