I'm not sure why this popped into my head just now.
There have been many fine graduate econometrics teachers/mentors; their armies of well-trained students now populate top universities. But two seem to me to have transcended the rest, achieving an almost mystical status: Tom Rothenberg and Denis Sargan. They trained many dozens of students on both sides of the Atlantic, and more generally they influenced the perspectives and careers of many thousands. (See, for example, the Rothenberg tribute volume edited by two fine Rothenberg students, Don Andrews and Jim Stock, and the Sargan bio by two fine Sargan students, David Hendry and Peter Phillips.) How did Rothenberg and Sargan do it? What was their secret? Surely an ethic of selfless giving played a huge role.
An interesting and puzzling thing (to me at least) is that, perhaps amazingly in our small academic world, I never met Tom or Denis. My loss, for sure.