Puzzle pieces have been adopted by many in the autism community as their symbol. I've heard a few explanations. First, autism is a puzzle that must be figured out. I can see truth in that. And I would add that each person with autism has his/her own solution. Second, the puzzle must be worked until all the pieces fit. That is some organization's tagline: "Until all the pieces fit", but I can't recall which org it is. Third, autism is puzzling. Yes, it can be, but I do try to stay away from negative, oppressive messages about autism. I don't want Thomas to hear that.
Not everyone is a big fan of the puzzle piece. I hear this especially from the self-advocates, saying that they are not puzzles to be fixed. They are who they are and they are not to be fixed. Who am I to argue with that? My respectful response to that sentiment is that while my son can't tell me what he needs, what hurts, if he's hungry or sick or scared, etc, etc, etc, then it is my job to figure that out. Anything less would be neglectful and dishonoring his very human qualities that need tending, especially as a child.