Don Keough was a hugely influential executive who helped shape Coca-Cola as it is today. Keough, who died on Feb. 24, was involved in many pivotal events during his long career. But no incident was bigger and more challenging than the ill-fated launch of New Coke 30 years ago today.

We combed through some of Keough’s remembrances of the era. Here are a few highlights:

On the initial, negative response from consumers:

“Negative calls to our hotline were reaching over 1,000 a day, disrupting Atlanta’s telephone circuits... One letter was from a lawyer in Idaho addressed to me, the president and chief operating officer, and Roberto Goizueta, chairman and chief executive officer. ‘Gentlemen, will the two of you please autograph the bottom of this letter because it will soon be worth a fortune. It will bear the name of the two dumbest @&$!!% in American business history.’ Roberto and I gamely signed.”

On the lessons of New Coke:

“I realized… that this was not a marketing issue; it was instead a deep psychological issue. A brand is not what you think it is; it is what is embedded in the mind of your user… We weren’t just playing around with a product; we were messing with an institution. And the American people let us know right away that they owned the brand.”

On test results for New Coke:

“Early taste tests showed that the new formula finished well ahead of our competitor, in one-sip taste tests. When people heard it was a new product from Coca-Cola, they got very excited. Consumers wanted it; that seemed clear… In the private taste tests, the new formula was being extremely well received.”

On admitting to the New Coke mistake:

“Most leaders of American companies begin to get a sense of infallibility and never want to admit a mistake. If you look at the annual reports of companies, except for Warren Buffett’s Berkshire Hathaway, everything is always perfect; no one ever made a mistake.”

On the announcement of the return of Coke Classic:

“We started to get love letters from everybody… It was like a Frank Capra script. Big company does something, the people rebel and you find out who owns the company and who owns the brand; the big company retracts its decision and then a great victory for the people comes as the end result of all this… I honestly believe a lot of the outpouring of good will from the public was because we made a simple acknowledgement that we got it wrong and that we were not infallible.”