It is because some of them share the pop...

It is because some of them share the popular error by which they themselves profit, while others profit by it without sharing it. Your Mr. Purgon has no wish to deceive; he is a thorough doctor from head to foot, a man who believes in his rules more than in all the demonstrations of mathematics, and who would think it a crime to question them. He sees nothing obscure in physic, nothing doubtful, nothing difficult, and through an impetuous prepossession, an obstinate confidence, a coarse common sense and reason, orders right and left purgatives and bleedings, and hesitates at nothing. We must bear him no ill-will for the harm he does us; it is with the best intentions in the world that he will send you into the next world, and in killing you he will do no more than he has done to his wife and children, and then he would do to himself, if need be.

Molière, The Imaginary Invalid, Project Gutenberg, 2012, pp. 95-96.