If all else fails, immortality can always be assured by adequate error.
John Kenneth Galbraith (1908-2006) Canadian-American economist, diplomat, author
Money: Whence It Came, Where It Went, ch. 13 “The Self Inflicted Wounds” (1975)
(Source)
Sometimes misquoted as "... by spectacular error".
Does anyone know how it got changed from adequate to spectacular?
I’m not able to easily find the divergence. The alternative is offered by the Oxford Dictionary of Quotations (https://www.oxfordreference.com/display/10.1093/acref/9780191826719.001.0001/q-oro-ed4-00004698#:~:text=by%20a%20spectacular%20error); they do not note when the change occured.
At a guess, “spectacular error” is more, well, “spectacular” than “adequate error,” more exciting, and thus once a misquote starts circulating, it has a small advantage over the original. The two end up meaning slightly different things (reputation from one, gigantic error, vs. from a record of ongoing, uncorrected errors), but close enough that it doesn’t seem intentional. I suspect that someone recalling the quotation by memory simply misquoted it, and others picked the change up.