Attributed to Maslow by Toni Galardi in The LifeQuake Phenomenon: How to Thrive (Not Just Survive) in Times of Personal and Global Upheaval (2009). Also to be found in other self-help books and on many quotes sites, but always without citation.
Quotes attributed to Abraham Maslow
“The persona can eventually become ourselves, or an aspect of ourselves, to the point where we don't know which is the mask and which is the I.”
From Certainty to Uncertainty (2002)
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F. David Peat 14
British physicist 1938–2017Related quotes

Source: Think Big (1996), p. 244

Commencement address at his daughter Linell's boarding school, as quoted http://www.washingtonpost.com/wp-dyn/content/article/2005/05/05/AR2005050501359_pf.html in The Washington Post (8 May 2005)
Context: Among other things I think humor is a shield, a weapon, a survival kit... So here we are several billion of us, crowded into our global concentration camp for the duration. How are we to survive? Solemnity is not the answer, any more than witless and irresponsible frivolity is. I think our best chance lies in humor, which in this case means a wry acceptance of our predicament. We don't have to like it but we can at least recognize its ridiculous aspects, one of which is ourselves.

Lecture IV : Objections
India, What Can It Teach Us (1882)

Source: Take The Risk (2008), p. 236

November 22, 1963; upon receiving news that President John F. Kennedy had died. (See A Thousand Days)
Attributed

As quoted in "The Farewell writer-director Lulu Wang on the joys of laughing at human nature" in The Verge (17 July 2019) https://www.theverge.com/2019/7/17/20696611/the-farewell-writer-director-lulu-wang-interview-awkwafina