Can you sleep? It seems like a simple question, but some alien races turn out to not know what sleep is. That is, they would like to learn, but for a couple of thousand years they haven’t been able to. And then, completely “by chance,” on one of the remote planets they meet two earthly guys. Who will be very happy to help them resolve this issue. Of course, for a small fee. Read what came of it in the story “Unfinished Higher Education.”