“Freedom suppressed and again regained bites with keener fangs than freedom never endangered.”

(2007) HARDtalk with Vaclav Klaus, BBC News, November 2007 http://www.youtube.com/watch?v=TEQmJBINYj4,

Book Three, Chapter XXII.
Democracy in America, Volume II (1840), Book Three

This quotation appeared in an article by Margaret Thatcher, "The Moral Foundations of Society" ( Imprimis, March 1995 https://imprimis.hillsdale.edu/the-moral-foundations-of-society/), which was an edited version of a lecture Thatcher had given at Hillsdale College in November 1994. Here is the actual passage from Thatcher's article:
<blockquote>[M]ore than they wanted freedom, the Athenians wanted security. Yet they lost everything—security, comfort, and freedom. This was because they wanted not to give to society, but for society to give to them. The freedom they were seeking was freedom from responsibility. It is no wonder, then, that they ceased to be free. In the modern world, we should recall the Athenians' dire fate whenever we confront demands for increased state paternalism.</blockquote>
The italicized passage above originated with Thatcher. In characterizing the Athenians in the article she cited Sir Edward Gibbon, but she seems to have been paraphrasing statements in "Athens' Failure," a chapter of classicist Edith Hamilton's book The Echo of Greece (1957), pp. 47–48 http://www.ergo-sum.net/books/Hamilton_EchoOfGreece_pp.47-48.jpg).
Misattributed

Source: Autobiography of a Spiritually Incorrect Mystic (2000), p. 25

In a phone interview with Maria Bartiromo on Fox News November 29, 2020
2020, November 2020

God or Nothing: A Conversation on Faith (2015)

Section 3 : Work Democracy versus Politics. The Natural Social Forces for the Mastery of the Emotional Plague;
Variant translation: The cry for freedom is a sign of suppression. It will never cease as long as man feels himself to be trapped. No matter how different the cries for freedom may be, at bottom they always express one and the same thing: the intolerableness of the organism's rigidity and the mechanical institutions of life, which are sharply at variance with the natural sensations of life. ... Not until man acknowledges that he is fundamentally an animal, will he be able to create a genuine culture.
The Mass Psychology of Fascism (1933), Ch. 10 : Work Democracy
Context: The cry for freedom is a sign of suppression. It will not cease to ring as long as man feels himself captive. As diverse as the cries for freedom may be, basically they all express one and the same thing: The intolerability of the rigidity of the organism and of the machine-like institutions which create a sharp conflict with the natural feelings for life. Not until there is a social order in which all cries for freedom subside will man have overcome his biological and social crippling, will he have attained genuine freedom. Not until man is willing to recognize his animal nature — in the good sense of the word — will he create genuine culture.

Address to the annual meeting of the Phoenix Chamber of Commerce (30 March 1961)
Later variant: Freedom is a fragile thing and is never more than one generation away from extinction. It is not ours by inheritance; it must be fought for and defended constantly by each generation, for it comes only once to a people. Those who have known freedom and then lost it have never known it again.
California Gubernatorial Inauguration Speech http://www.reagan.utexas.edu/archives/speeches/govspeech/01051967a.htm (5 January 1967)
1960s
Context: Freedom is never more than one generation away from extinction. We didn’t pass it on to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same, or one day we will spend our sunset years telling our children and our children's children what it was once like in the United States where men were free.

7 May 1944
(1942 - 1944)
Source: The Diary of a Young Girl