Why did the monster feel rejection?

Shortly thereafter, he arrives in Geneva. Once again, a child runs past his hiding-place in the deep woods. The creature is much taken with the beautiful child, and speculates that he is still too young to feel hatred for his deformity. He seizes the boy's arm as he runs past; the child screams in terror and struggles to get away. He calls the creature a "hideous monster," and says that his father, M. Frankenstein, will punish him.