flowers of algernon

Fanny uses a Biblical allusion to Charlie accessing knowledge that should have otherwise be forbidden to him:

"...it's not meant for man to know more than was given to him to know by the Lord in the first place. The fruit of that tree was forbidden to man."

She likens Charlie's quest for greater intelligence to the situation of Adam and Eve in the Garden of Eden. She thinks it a sin that Charlie has been altered to gain this knowledge.