The humanoids on Trill shared the planet with sentient vermiforms called symbionts. The symbionts could live inside the body of a humanoid Trill, and that symbiotic relationship conferred upon the Trill the memories and life experience of every host in which the symbiont had lived before. It was a high honor among Trill to be joined with a symbiont, and the Symbiosis Commission selected among the most accomplished young adult Trill for the privilege. The Trill who were chosen to be joined were also the most psychologically fit, though that didn't mean they didn't feel some jitters during the invasive procedure. The humanoid host for the Ret symbiont was very near death, and in the operating room, the weight of what was about to happen began to bear on young Mika. "How are you", said the doctor, rhetorically. "I... don't know", Mika said. "A little nervous, I know. Let's give you a little sedative to take the edge off", the doctor said, gesturing toward a nurse, who set forth adding a sedative to the drip feed. "Mika", the doctor said evenly, "I'm about to apply the anaesthetic gel to the incision point. It's a little chilly." The young Trill woman jerked at the cold, despite the warning and the systemic anaesthetic. "Still a wee bit jumpy" the doctor said, with warmth and experience. "You want to hear a joke? I know an old joke from Earth. It... how do you say, kills, but we will avoid that." The Trill doctor continued. "A patient has just undergone a procedure, and the doctor says: 'The procedure went without a hitch, complete success.' " "The patient says: 'Oh, good! I am so relieved! Doctor, will I be able to play the piano?', and the doctor says: 'Well, certainly'. 'Wow,' says the patient, 'because I never could before'." Then there was silence, which suggested the end of the joke. Mika said: "Is that it? I don't get it." "You see, on Earth that question about playing piano only makes sense if the patient could play piano before. It's such a specific question that the doctor must assume that the patient could already play piano, and because that procedure, whatever it was, would not affect that, doctor says 'yes, sure', and the part that is funny on Earth is that the patient could not. I tell that joke here on Trill, because hey, you never know with the symbionts and their previous hosts, maybe you can play the banjo or whatever..." Mika begins to tune out the doctor's long-winded explanation of a joke that wasn't very funny to begin with, and the doctor says: "We are finished. You rest for a bit... Mika Ret."