What role does the last paragraph play in the passage?

Answer this question based on the following passage.

            The old maxim, that "Knowledge is Power," 
            is a true one, but there is still a greater truth:
            "Knowledge Is Safety." Safety amid physical
            ills that beset mankind, and safety amid the
(5)        moral pitfalls that surround so many young 
            people, is the crying demand of the age. 
            Research has thrown light on many facts 
            relating to the physiology of man and 
            woman, and the diseases to which they are
(10)      subject, and consequently many reformations
            have taken place in the treatment and 
            prevention of diseases. Any information bearing
            upon the diseases of mankind should not be
            kept under lock and key. The physician is
(15)      frequently called upon to speak in plain 
            language to his patients about disease 
            contracted on account of ignorance. The 
            better plan, however, is to so educate and 
            enlighten old and young upon the important 
(20)      subjects of health, that the necessity to 
            call a physician may occur less frequently.
            A large, respectable, though diminishing 
            class in every community, maintain that 
            nothing that relates exclusively to either sex 
(25)      should become the subject of popular medical
            instruction. But such an opinion is radically 
            wrong; ignorance is no more the mother of 
            purity than it is of religion. The tendency in 
            the right direction must be admitted, and is
(30)      perhaps most clearly shown in some of the 
            articles on prison reform. Preventive work is
            the truest economy. Some go so far as to say
            that if the present human knowledge of the
            laws of heredity were acted upon for a 
(35)      generation, reformatory measures would be 
            rendered unnecessary. 
            Perhaps nothing will so much hasten the time
            when body and mind will both be adequately 
            cared for, as a diffusion of the belief that the 
(40)      preservation of health is a duty. Few seem 
            conscious that there is such a thing as physical 
            morality. The fact is, all breaches of the law of 
            health are physical sins. Men's habitual words 
            and acts imply that they are at liberty to treat 
(45)      their bodies as they please. Though the evil
            consequences inflicted on their descendents 
            and on future generations are often as great 
            as those caused by crime, they do not think 
            themselves in any degree criminal. Purity of 
(50)      purpose and purity of character, after all, 
            are the brightest jewels in the crown of 
            immortality.