Raban Gamliel (the leader of the Jews of Galilee after the destruction of the Temple by the Romans) and Rabbi Yehoshua were together on a ship. Raban Gamliel had brought bread; Rabbi Yehoshua, bread and flour. When Raban Gamliel's bread ran out, they subsisted on the flour.
Raban Gamliel: How did you know we'd be delayed, and need flour?
Rabbi Yehoshua: There's a star in the sky, and once in 70 years it confuses sailors and they lose their way. I feared we might be affected and so brought additional flour.
Raban Gamliel: If you're so wise, how did you allow yourself on a ship in the first place? Couldn't you make a living with less danger? [Sea faring in those days was rather often fatal, a subject often discussed in the Talmud].
Rabbi Yehoshua: If you're wondering about me, think of your two students Rabbi Elazar Hisma and Rabbi Yochanan ben Gudgeda, who are so intelligent they can compute the number of water drops in the sea, yet they don't earn enough to feed or clothe themselves!
Raban Gamliel decided to promote them. When he returned to port he had them summoned, but they didn't appear. He summoned them again, and this time they came. When they came he said to them:
You think I'm offering you power and honor (שררה)? That's why you didn't come the first time? Indenture is what I'm giving you [since leadership posts carry obligations to the people]. As it is said (1 Kings chapter 12 verses 6-7)
And king Rehoboam consulted with the old men, that stood before Solomon his father while he yet lived, and said, How do ye advise that I may answer this people?
7And they spake unto him, saying, If thou wilt be a servant unto this people this day, and wilt serve them, and answer them, and speak good words to them, then they will be thy servants for ever.
This thread is introduced and explained here.