“I don't need a friend who changes when I change and who nods when I nod; my shadow does that much better.”
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Plutarch 251
ancient Greek historian and philosopher 46–127Related quotes
Source: The Tides of Time (1984), Chapter 12 (p. 220)

“I am displeased when sometimes even the worthy Homer nods;”
Indignor quandoque bonus dormitat Homerus;
Whence the familiar expression, Even Homer nods (i.e. No one is perfect: even the wisest make mistakes).
Source: Ars Poetica, or The Epistle to the Pisones (c. 18 BC), Line 359

“Don't write when you can talk; don't talk when you can nod your head.”
Van Nostrand, Albert D. (December 1948). "The Lomasney Legend". The New England Quarterly. 21 (4): 437. JSTOR 361565 https://www.jstor.org/stable/361565

As quoted in Cracking the Code of Our Physical Universe : The Key to a Whole New World of Enlightenment and Enrichment (2006) by Matthew M Radmanesh, p. 91

Warning to criminals.
Pressure Mounts on Spitzer to Resign Over Sex Scandal, PBS NewsHour, March 11, 2008, 2012-10-15 http://www.pbs.org/newshour/bb/law/jan-june08/spitzer_03-11.html,