“Do you know the definition of insanity? Doing the same thing over and over and expecting different results."

"Wrong. That's the definition of determination.”

Variously attributed also to Benjamin Franklin and Mark Twain. The earliest known occurrence, and probable origin, is from a 1981 text from Narcotics Anonymous: "Insanity is repeating the same mistakes and expecting different results." Cf. Rita Mae Brown#Misattributed.
Misattributed
Variant: Insanity: doing the same thing over and over again and expecting different results.

Source: Scar Tissue

Rich Dad Poor Dad: What the Rich Teach Their Kids About Money-That the Poor and the Middle Class Do Not!

Brown did include this quote in her book Sudden Death (Bantam Books, New York, 1983), p. 68, but it appears she was just paraphrasing a quote that had already been written elsewhere. The earliest known appearance of a similar quote is the "approval version" of the Narcotics Anonymous "Basic Text" released in November 1981, which included the quote "Insanity is repeating the same mistakes and expecting different results." A PDF scan of the 1981 approval version can be found here http://www.nauca.us/wp-content/uploads/2015/04/1981-11-Basic-Text-Approval-Form-White.pdf, with the quote appearing on p. 11 (p. 25 of the PDF), at the end of the fourth paragraph (which begins "We have a disease; progressive, incurable and fatal"). More in this article https://quoteinvestigator.com/2017/03/23/same/ on Quote Investigator website.
Misattributed

Source: Sudden Death

Source: Revolutionary Road

To question genetic intelligence is not racism (2007)
Context: We do not yet adequately understand the way in which the different environments in the world have selected over time the genes which determine our capacity to do different things. The overwhelming desire of society today is to assume that equal powers of reason are a universal heritage of humanity. It may well be. But simply wanting this to be the case is not enough. This is not science.
To question this is not to give in to racism. This is not a discussion about superiority or inferiority, it is about seeking to understand differences, about why some of us are great musicians and others great engineers. It is very likely that at least some 10 to 15 years will pass before we get an adequate understanding for the relative importance of nature versus nurture in the achievement of important human objectives. Until then, we as scientists, wherever we wish to place ourselves in this great debate, should take care in claiming what are unarguable truths without the support of evidence.

20:00–20:38
"Nirvana's Krist Novoselic on Punk, Politics, & Why He Dumped the Dems" https://www.youtube.com/watch?v=k4TPRH2uK9w