Why does society reject the monster?

[Showtime]

Because of his physical deformities, Frankenstein's monster is rejected by society throughout the novel summed up in Victor Frankenstein's own words, "its unearthly ugliness rendered it almost to horrible for human eyes."

What does the response to the monster say about society as a whole? Is it surprising? How does the monster experience this rejection? What is the lesson Shelly is trying to convey?