John Stuart Mill (1806-1873) & John Milton (1608-1674).Defenders of Free Speech

This is true Liberty when free born men
Having to advise the public may speak free,
Which he who can, and will, deserves high praise,
Who neither can nor will, may hold his peace;
What can be juster in a State then this?

Euripides, translated by John Milton for the title page of his  Areopagitica: A Speech of Mr John Milton for the Liberty of Unlicensed Printing, to the Parliament of England(1644)

Dag Hammarskjöld, from his book Markings: 

Respect for the word is the first commandment in the discipline by which a man can be educated to maturity—intellectual, emotional and moral. 

Respect for the word—to employ it with scrupulous care and an incorruptible heartfelt love of truth—is essential if there is to be any growth in a society or in the human race. 

To misuse the word is to show contempt for man. It undermines the bridges and poisons the wells. It causes Man to regress down the long path of his evolution.

...........

“We can never be sure that the opinion we are endeavouring to stifle is a false opinion; and even if we were sure, stifling it would be an evil still. First, if any opinion is compelled to silence, that opinion may, for aught we can certainly know, be true. To deny this is to assume our own infallibility. Secondly, though the silenced opinion be an error, it may, and very commonly does, contain a portion of truth; and since the general or prevailing opinion on any object is rarely or never the whole truth, it is only by the collision of adverse opinions that the remainder of the truth has any chance of being supplied. Thirdly, even if the received opinion be not only true, but the whole truth; unless it is suffered to be, and actually is, vigorously and earnestly contested, it will, by most of those who receive it, be held in the manner of a prejudice, with little comprehension or feeling of its rational grounds. And not only this, but, fourthly, the meaning of the doctrine itself will be in danger of being lost, or enfeebled, and deprived of its vital effect on the character and conduct: the dogma becoming a mere formal profession, inefficacious for good, but cumbering the ground, and preventing the growth of any real and heartfelt conviction, from reason or personal experience.” 

John Stuart Mill,  in picture below. (1806-1873) 

“Though all the winds of doctrine were let loose to play upon the earth, so Truth be in the field, we do injuriously, by licensing and prohibiting, to misdoubt her strength. Let her and Falsehood grapple; who ever knew Truth put to the worse, in a free and open encounter?”

I have sat among their learned men, for that honour I had, and been counted happy to be born in such a place of philosophic freedom, as they supposed England was, while themselves did nothing but bemoan the servile condition into which learning amongst them was brought; that this was it which had damped the glory of Italian wits; that nothing had been there written now these many years but flattery and fustian. There it was that I found and visited the famous Galileo, grown old, a prisoner to the Inquisition, for thinking in astronomy otherwise than the Franciscan and Dominican licensers thought.

John Milton (1608-1674) visiting Galileo.