The lecture circuit:
"Another morning comes: I see,
Dwindling below me on the plane,
The roofs of one more audience
I shall not see again.
God bless the lot of them, although
I don't remember which was which:
God bless the U.S.A ., so large,
So friendly, and so rich."
From W.H. Auden's paean to America's lecturing goldmine, "On the Circuit," read by the poet here.