Literal

I took a class during my senior year of high school, and my teacher posed this question. Does Gregor S. literally turn into a bug through a metamorphosis, or could this metamorphosis be a metaphor for a change within him after an epiphany within his society which allowed him to view himself as a bug, a vermin, something that society does not want, but rather he must continue to live regardless. Also, does the metamorphism wear off and return him to a human form by the end of the book? I pose these questions: Does he go through an altered state of mind during the metamorphosis, and eventually learn how to cure himself within society without necessarily changing the people's opinions around him? Pay close attention to the descriptions of his life within the state of the bug, and see how the bug crawls away from him if at all. Does he remain where he is? Does he learn anything, or was this metamorphosis posed on him from society? Does he have the ability and free will to change this, or is he merely stuck as a bug in this form, awaiting his fate in the end. Also, try to pay attention to the use of color and literal sense of the environment. My teacher during the time when I read this book for the first time posed another question. What other metaphors can be found in this book? Are there any literary illusions to other books? What about the metaphor about the apple thrown at Gregor by his father. I concluded with most of the class that it could be interpreted in two senses of reality. Is it a metaphor for the Garden of Eden in the first book of the Genesis, or is it a much more literal sense of reality in which the characters play?