Ah teaching, the sharing of knowledge from one to another, and then another to others. It's like a bittorrent swarm that's just starting up. At first, one holds all the knowledge, shares it out a chunk at a time, and then that recipient can share the knowledge too. If it works, pretty soon everybody is sharing knowledge and everyone has all the pieces, and newcomers are inundated with knowledge as fast as they can take it in. No longer are they limited by the amount of teachers - everybody is a teacher.
A most curious part of teaching, however, is that in teaching, you also learn a lot. The equivalent bittorrent analogy is that no individual has all the pieces, but collectively, a full copy exists. Only by sharing, can the pieces be put together, and everybody is better off for it (ignoring throughput costs).
plz seed knowledge