Imagination is more important than knowledge. Knowledge is limited. Imagination encircles in the world. And at times, even beyond. Imagination creates scenarios for bloom, gloom and doom. Thus they say, we are what we imagine !
Let your imagination fly. Give it wings for only then will you atleast reach the tree tops. Aid it with a spade and it can dig you your own graveyard. Let your interns imagine and boldly tell you they want the top job. For therein lies his ambition which will make him work to reach the top....
It is a win-win way for you will have a dedicated resource in the system working to the top.