The right stuff
If I were William Safire, I might try to track down the first use of the expression “the right stuff,” especially as it applies to daring achievements by men. It’s certainly much older than Tom Wolfe’s 1979 book about test pilots and astronauts.
I’ve just finished reading Teddy Roosevelt’s lively and argumentative autobiography, in the Library of America edition, and noticed two instances (pp. 440-441 and pp. 486-487) where he uses “the right stuff” in the modern sense. The first comes from the chapter describing his time as New York City Police Commissioner, and the second is from the chapter on being the governor of New York.
Occasionally a policeman would perform work which ordinarily comes within the domain of the fireman. In November, 1896, an officer who had previously saved a man from death by drowning added to his record by saving five persons from burning.... Whenever I see the police force attacked and vilified, I always remember my association with it. The cases I have given above are merely instances chosen almost at random among hundreds of others. Men such as those I have mentioned have the right stuff in them!
If ever we have a great war, the bulk of our soldiers will not be men who have had any opportunity to train soul and mind and body so as to meet the iron needs of an actual campaign. ... But if the men have in them the right stuff, it is not so very difficult.

