The only thing evil needs to prevail is for good men to do nothing~Edmund Burke
It has been attributed to Edmund Burke, Irish born Whig politician and man of letters. There is no record that Burke said this. The quotation became popular after John F. Kennedy began using it in speeches but after careful research by many persons, no source could be found. Bartlett's discontinued attributing the saying to Burke. How this got misattributed to Burke is anybody's guess.
The most likely originator of the quote: Bad men need nothing more to compass their ends than that good men should look on and do nothing.~John Stuart Mill, "On Education" (1867)
* * * Since we are destined to live out our lives in the prison of our minds, our one duty is to furnish it well~Peter Ustinov