"It's not just bullet points. It's supposed to create the context for the discussion. No PowerPoints are used inside Amazon."
Bezos said when new executives are hired they are warned: "This is the weirdest meeting culture you ever encounter."
He explained the meetings are "so much better than the typical Power-Point presentation for so many reasons' because a 'brilliant and thoughtful" memo can "set up the meeting for high-quality discussion".
"We read in the room. Just like high-school kids, executives [elsewhere] will bluff their way through the meeting as if they've read the memo.
"So you have to carve out time so everyone has actually read the memo - they are not just pretending."
Earlier this year Jeff Bezos, already the world's richest person, added another US$20 billion ($28.5b) to his wealth after his firm Amazon reported its largest ever surge in profits.
In a recent letter to shareholders he said some executives believe memos can be written in a few hours when "a great memo probably should take a week or more".
"Not surprisingly, the quality of these memos varies widely," said Bezos.
"Some have the clarity of angels singing. They are brilliant and thoughtful and set up the meeting for high-quality discussion. Sometimes they come in at the other end of the spectrum.
"It would be extremely hard to write down the detailed requirements that make up a great memo.
"Nevertheless, I find that much of the time, readers react to great memos very similarly. They know it when they see it. The standard is there, and it is real, even if it's not easily describable."