The Future

"Like you say, Kath.  We're going to be leaving her soon.  It's not like a game any more.  We've got to think carefully."  As they are about to leave Hailsham, the students, mainly Tommy, Ruth, and Kathy were talking about their future.  Ruth wants to be back together with Tommy.  My opinion on that is that Kathy and Tommy will somehow end up together.  Also, Miss Lucy told Tommy that his art is evidence.  But the question is, evidence for what?  I think the evidence is for after they are done giving their organs, there will be proof that they once existed.  However, that may be an unreasonable assumption.  However, at the end of the chapter, Miss Lucy left, or "had been told to leave" Hailsham. I am wondering the reasoning behind it!