The question below consists of a set of labelled sentences. Out of the four options given, select the most logical order of the sentences to form a coherent paragraph.

P: It has been the handmaid of the ruling class.
Q: Therefore, ever since the dawn of civilization, persons in power have always tried to supervise or control education.
R: Education is an instrument which imparts knowledge and therefore, indirectly controls power.
S: It is an old saying that knowledge is power.