On 12 March 1969, NASA's Assistant Administrator for Public Affairs, Julian Scheer, wrote a memo to George Low, the Apollo Spacecraft Program Manager. Scheer had learned, to his horror, that Low was seeking advice on how coach the crew of Apollo 11 (Neil Armstrong, Buzz Aldrin and Micheal Collins) on what rousing and inspiring words to say for the history books, once they arrived at the Moon. Scheer cited numerous examples of great explorers such as James Cook, William Clark and Robert Peary to illustrate the poignance of honest, unfiltered first words.

In December the previous year, the crew of Apollo 8 had made history by visiting the Moon and returning to Earth without a landing - a trial run for the upcoming programme of landings. The crew had pre-prepared to read from the Book of Genesis during their lunar flyby on Christmas Eve 1968. Scheer refers to this in his memo:
Frank Borman [Commander, Apollo 8] solicited a suggestion from me on what would be appropriate for Christmas Eve. I felt-and my feeling still stands-that his reading from the Bible would be diminished in the eyes of the public if it were thought that NASA pre-planned such a thing. I declined both officially and personally to suggest words to him despite the fact that I had some ideas. I believed then and I believe the same is true of the Apollo 11 crew that the truest emotion at the historic moment is what the explorer feels within himself not for the astronauts to be coached before they leave or to carry a prepared text in their hip pocket.
Scheer CC'd the crew of Apollo 11, and there is little doubt that they read it. Neil Armstrong, first person to set foot on the Moon, seems to have taken much inspiration from the figures raised in the note, as well as the need to express himself rather than NASA, per Scheer's closing remark:
The words of these great explorers tell us something of the men who explore and it is my hope that Neil Armstrong or Buzz Aldrin will tell us what they see and think and nothing that we feel they should say.
In our daily lives, we earthlings can scarcely comprehend the pressure Armstrong faced in his duty as the first ambassador to the lunar surface. To do something so unprecedented and dangerous, performing in front of virtually the entirety of humanity, who had never been so universally arrested by any event in history - it's astonishingly far from our everyday experience. Apollo 11's approach to the landing site had not happened without incident. The crew famously adjusted their planned trajectory to avoid unfavourable terrain, running alarmingly low on fuel in search of a safer site. Cool heads prevailed, and on 20 July 1969 - about four hours after touchdown - 38-year-old Armstrong emerged from the lunar lander to descend the ladder and place the first footprint on the Moon. Broadcast live to every corner of the world, he uttered an immortal statement that would be quoted by every news organisation on Earth:
That's one small step for Man, one giant leap for mankind.

Except that's not what Armstrong actually said. He was misquoted, and his actual words were both more personal - the honest reflections of the explorer - and more sensical. According to Armstrong, he really said:
That's one small step for a man, one giant leap for mankind.
With Man and mankind being synonymous, it is more reasonable to assume that Armstrong was thinking about the weight of responsibility that one individual can carry on behalf of their people, and intended to refer to himself. Perhaps owing to the quality of the microphone, signal and broadcast, the "a" was lost, but subsequent audio analysis has shown that he most likely did vocalise it, and NASA has officially backed him up.

We can only speculate on his thoughts and emotions in the hours approaching the historic first step - Armstrong was a reserved individual who largely retired from public life after his heroic career as an astronaut - but upon his return to Earth, he did share his thoughts about his first words:
I thought about it after landing, and because we had a lot of other things to do, it was not something that I really concentrated on, but just something that was kind of passing around subliminally or in the background. But it, you know, was a pretty simple statement, talking about stepping off something. Why, it wasn’t a very complex thing. It was what it was.
It seems Armstrong did not overthink it, nor did he likely have much time to overthink it. What he said reflected what he felt within himself, and perhaps that is why - even misquoted - it resonated with so many here on Earth.

When asked about the misquoted "small step" statement in 1999, 30 years after Apollo 11, Armstrong gave a humble and accommodating reply that seemed apt for his relaxed personality:
The ‘a’ was intended. I thought I said it. I can’t hear it when I listen on the radio reception here on Earth, so I’ll be happy if you just put it in parentheses.
Neil Armstrong sought a quiet life after making history, and there are few who deserve it more. He delivered inspiring actions and words to billions - all under immense pressure and personal risk - and remained a steadfast advocate for spaceflight and exploration even during his media-shy years. His name and achievements are truly legendary. Armstrong passed away aged 82, on 25 August 2012. 

Image credits: NASA/AP, NASA