Parable: Who learned anything

The teacher half a century spent in school and now accompanied him on a holiday. In the hall were gathered many of his students. Among them were teachers and scientists, doctors and athletes, managers and workers, soldiers and priests, policemen and criminals, artists, actors and people with no special talents, distinguished and ordinary people. Many taught for my life teacher.
Before parting words they said:
- You, probably, someone of his disciples proud, and for whom you feel ashamed?
The teacher said:
- No, not proud and not ashamed of it, but only happy for you - after all, everyone learned what he studied.