Flowers for Algernon

From the text:

1) He raised his eyebrows, but let it pass. "Well, as we told her, in the event that the experiment failed, we couldn't send you back to the bakery or to that room where you came from."

2) "For one thing, you might not be the same. Surgery and injections of hormones might have had effects not immediately evident. Experiences since the operation might have left their mark on you. I mean, possibly emotional disturbances to complicate the retardation; you couldn't possibly be the same kind of person-"

3) "And for another thing there's no way of knowing if you would go back to the same mental level. There might be regression to an even more primitive level of functioning."