“If you only have a hammer, you tend to see every problem as a nail.”
“I like friends who have independent minds because they tend to make you see problems from all angles.”
Nelson Mandela on friendship, From his unplubished autobiographical manuscript written in 1975. Source: From Nelson Mandela By Himself: The Authorised Book of Quotations © 2010 by Nelson R. Mandela and The Nelson Mandela Foundation http://www.nelsonmandela.org/content/mini-site/selected-quotes
1970s
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Nelson Mandela 143
President of South Africa, anti-apartheid activist 1918–2013Related quotes

Re: Guide to Lisp, v1.20 http://groups.google.com/group/comp.lang.lisp/msg/f7bc99564506e851 (Usenet article).
Usenet articles, Miscellaneous
Source: "Historical and theoretical issues in the problem of modern capitalism", 1928, p. 143

At an event sponsored by the Center for American Progress, October 18, 2006[citation needed]
2000s
Source: The Untethered Soul: The Journey Beyond Yourself

Source: My Horizontal Life: A Collection of One-Night Stands

Weather (p. 159)
Short fiction, Galactic North (2006)

Question, Léger once called you a realist. How do you feel about this?
1950s - 1960s, interview with Alexander Calder', (1962)