“The mentality of mankind and the language of mankind created each other.”

Outre-Mer.

As quoted by Mussolini in 2000 Years of Disbelief: Famous People with the Courage to Doubt by James A. Haught (1966) p. 256. From a speech he made in Lausanne, July 1904.
1900s

On Seeing Plays (1990).
Context: It is mankind's discovery of language which more than any other single thing has separated him from the animal creation. Without language, what concept have we of past or future as separated from the immediate present? Without language, how can we tell anyone what we feel, or what we think? It might be said that until he developed language, man had no soul, for without language how could he reach deep inside himself and discover the truths that are hidden there, or find out what emotions he shared, or did not share, with his fellow men and women. But because this greatest gift of all gifts is in daily use, and is smeared, and battered and trivialized by commonplace associations, we too often forget the splendour of which it is capable, and the pleasures that it can give, from the pen of a master.

Source: The Stone That Never Came Down (1973), Chapter 23 (p. 180)

As quoted by Paul Wolfowitz in an address to the Washington Institute for Near East Policy, Washington, D.C. (13 March 2002) http://www.defenselink.mil/speeches/speech.aspx?speechid=198
Context: Mankind is a single body and each nation a part of that body. We must never say "What does it matter to me if some part of the world is ailing?" If there is such an illness, we must concern ourselves with it as though we were having that illness.

No. 1, volume v, p. 331
Letters On a Regicide Peace (1796)

The Liberty of Man, Woman and Child (1877)
Context: Nothing has been left undone by the enemies of freedom. Every art and artifice, every cruelty and outrage has been practiced and perpetrated to destroy the rights of man. In this great struggle every crime has been rewarded and every virtue has been punished. Reading, writing, thinking and investigating have all been crimes.
Every science has been an outcast.
All the altars and all the thrones united to arrest the forward march of the human race. The king said that mankind must not work for themselves. The priest said that mankind must not think for themselves. One forged chains for the hands, the other for the soul.

1960s, Freedom From The Known (1969)
Context: There has been outward progress from the bullock cart to the jet plane but psychologically the individual has not changed at all, and the structure of society throughout the world has been created by individuals. The outward social structure is the result of the inward psychological structure of our human relationships, for the individual is the result of the total experience, knowledge and conduct of man. Each one of us is the storehouse of all the past. The individual is the human who is all mankind.

Source: A Treatise On Political Economy (Fourth Edition) (1832), Book I, On Production, Chapter II, p. 69