Don't know the poem but I know a joke...
A rich doctor was at his local repair shop when a mechanic says to him
"How come you guys get the big bucks and i can barley make a living?"
"I mean take a look at this head, its just like a human heart, its got valves that let the lifes blood of the engine in and out."
"I can take it out, rebuild it, and put it back in making the engine run better than it ever has before. See our jobs are just alike!"
The doctor leans over and says...
"Try doing it with the engine running."