I loved him with a mixture of affection and reverence that knew no bounds, yet I could never persuade myself to confide to him that event which was so often present to my recollection, but which I feared the detail to another would only impress more deeply.

In this Chapter 6 quote, Victor describes his deep love and admiration for Henry Clerval. But despite their bond, Victor can't bring himself to confess the terrible truth about the creature he made, and his guilt and fear isolate him from one of his closest friends. As the book goes on, Victor's shame drives him further and further away from human connection, and his secrecy about the creature has deadly consequences.

Read more about the Harmful Effects of Isolation and Alienation as a theme. 

A flash of lightning illuminated the object, and discovered its shape plainly to me; its gigantic stature, and the deformity of its aspect, more hideous than belongs to humanity, instantly informed that it was the wretch, the filthy demon to whom I had given life.

This Chapter 7 quote occurs as Victor travels home after hearing the news that William has been murdered. In the midst of a storm, Victor believes he sees his creature, and he suddenly realizes that the monster he created is responsible for William's death. His visceral reaction is one of absolute horror; he describes him as "hideous," "a wretch," and a "filthy demon," terms that reveal how deeply disgusted and frightened he is of the being that he once believed would be his greatest achievement. 

Read more about the monster as the story's antagonist.  

A thousand times rather would I have confessed myself guilty of the crime ascribed to Justine ; but I was absent when it was committed, and such a declaration would have been considered as the ravings of a madman, and would not have exculpated her who suffered through me.

In this Chapter 8 quote, Victor explains why he didn't intervene on Justine's behalf when she was accused and convicted of murdering William, despite knowing that his monster was guilty of the crime. His weak justification for allowing an innocent girl to die reveals his own cowardice and is yet another instance when he claims that a terrible occurrence (i.e. the creation of the monster, Justine's conviction) was unavoidable, and therefore not his fault.

Read an in-depth analysis of Justine Moritz.

Thus spoke my prophetic soul, as torn by remorse, horror, and despair, I beheld those I loved spend vain sorrow upon the graves of William and Justine, the first hapless victims to my unhallowed arts.

In this Chapter 8 quote, Victor reflects on the devastating consequences of his ambition and acknowledges that his actions have destroyed the people he loves most. By calling Justine and William "the first hapless victims to my unhallowed arts,” Victor recognizes that his own reckless, foolish attempts to play God have led to their deaths. His remorse and despair here underscore the novel’s themes of dangerous knowledge and the consequences of ambition.

Read more quotes about the dangers of ambition.